Worldwide extension of concordats (1107-2017)
Concordats are no longer agreements between the pope and a Catholic king, as they were when they began. Now they are being extended to countries without a Catholic majority, or even a Christian majority. By the beginning of 2017 the Vatican had at least one concordat or more with over 50 countries.
The number of concordats has grown exponentially. After the first concordat was signed in London in 1107 there were only six more until 1700, averaging only one a century. During the eighteenth century fifteen more were made and in the nineteenth century a much larger number.  By the start of 2017 the Vatican had at least one concordat with over 50 states.  Some countries like Germany and Italy have dozens apiece.
Europe was where concordats began, but during the Protestant Reformation many of the concordats in Northern Europe were cancelled. At present European concordats are concentrated in the traditionally Catholic areas of the south and east. However, they are continually being extended, even to regions with a minuscule Catholic population like Schleswig-Holstein, the German state on the border with Denmark.
Of the 27 countries of the European Union, 15 are bound to the Holy See by at least one concordat: Germany (at both federal and state levels), Austria, Spain, Italy, Portugal, Luxemburg, Estonia (1998), Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia, and even three concordats with the supposedly secular France.
Latin America now has many concordats, despite the widespread cancellation of its earlier ones. 
In the Islamic world there are a number of diplomatic agreements of various kinds with Islamic States and other bodies. The first agreements with Israel (1993 and 1997) were followed by one with the Palestinian Authority (2002). There are also a 1964 modus vivendi with Tunisia, the 1983-84 exchange of diplomatic notes with Morocco, an agreement on bilateral relations with Kazakhstan (1998) and also with Albania (2002).  Cautious concordat overtures have been started with Saudi Arabia which signed a limited "memorandum of understanding" in 2016, on the mutural recognition of diplomatic passports.  Another “memorandum of understanding” (2009) was signed with the League of Arab States which curently has 22 members. This was supposed to foster "interreligious dialogue", but the American State Department suspected that the timing was political as "a tangible gesture to its Arab and Muslim partners on the eve of the Pope's visit to Israel, to demonstrate the Church's even-handedness and credibility".  In 2013 the Vatican expanded its inter-regional presence, both in Central America, where it became an Extra-Regional Observer to the Sistema de la Integración Centroamericana, and in Africa, with its accreditation as the first Permanent Observer to the Economic Community of West African States. 
It has taken longer to get concordats with overwhelmingly Orthodox Christian states than with Islamic ones. However, the first one, with Montenegro, was ratified until in 2012. The incentive appears to be Montenegro's hope that the Vatican will help it gain entry to the European Union.  Two years later a concordat was signed with Serbia to allow Catholic schools. The Vatican overcame Serbian resistence, fuelled by memories of the Croatian Holocaust, through the same stratagem it used to push through the 2008 concordat with France. It described this education concordat as simply the result of the European push to harmonise the recognition of academic degrees. 
Africa, Asia and Oceania are the current growth areas for the Catholic Church. 
In Africa concordats have not been limited to individual states and in 2000 an agreement was signed with the Organisation of African Unity (text).  Concordats have also been signed with Gabon (2009) , Côte d'Ivoire, Mozambique (2011) , Burundi (2012) , Equatorial Guinea (2012) , Cape Verde (2013) , Chad (2013) , and framework concordats with Cameroon (2014) , the Democratic Republic of Congo (2014), the Central African Republic (2016) , Benin (2016)  and the Republic of Congo [2017) , with many more in the works.
Africa was home to almost 200 million Catholics in 2015 , and by 2025 the projected 230 million Catholics will represent one-sixth of all Church members worldwide.  On a continent where the Catholic Church offers many services that states do not, Africa is widely seen as the future of the Church.  It also offers the chance to cement concordats with de facto dictators, which remain even when countries become more democratic. For example, the Vatican's cryptic new release says that this concordat "provides for the implementation of functional understandings between the Bishops’ Conference and the State on certain matters of common interest". Who knows what the authoritarian ruler of the troubled DR Congo has ceded to the Church?
Asia is another area where the Vatican has recently extended the reach of concordats. By the end of Benedict XVI's reign in 2013 the Vatican had ties with 180 countries, though the Pope had been unable to achieve the “core goals” of formal diplomatic ties with Saudi Arabia, China, and Vietnam.  However, in 2011 the Vatican made an agreement with Hanoi which made the necessary concessions: the nomination of bishops had to be approved by both the Vatican and the Vietnamese government. This amounts to the privilege of royal patronage which was first accorded to powerful mediaeval kings who insisted on having a say in choosing the bishops in their realms, and has since been quietly extended to any country which will not accept complete Church control.
It wasn't until 2012 that the Vatican finally got a concordat with a Chinese nation. This opening was due to the feeling of international isolation by the Republic of China (Taiwan). Eager to prevent the Vatican from transferring diplomatic recognition to its rival, the People's Republic, Taiwan made an education concordat which functioned as an acknowledgement of Vatican recognition. 
This was a vain hope, of course, as the Vatican is particulary eager to get China, home to a fifth of the world's population, opened up for missionising. There had been a standoff in China, with both the Vatican and the Chinese government insisting on the right to appointing bishops. This led to two rival Catholic groups in China, the party-controlled Chinese Catholic Patriotic Association and the Vatcian-compliant "underground" Catholic Church. However, in 2016 a compromise, whose text has not been released, was hammered out. According to Cardinal John Tong Hon, the pope will choose from a list of candidates recommended by a conference of bishops from both the open and clandestine churches. In other words, the Vatican has found itself obliged, at least for now, to grant the Chinese Communist Government some say. Citing the “Vietnam model”, Tong said the practice of appointing bishops may be adjusted to what was feasible in the local situation. 
Of course, concordats are not the only way the Vatican inserts itself as a state into the legal framework of the world. The Vatican has relations with many supranational bodies, as well. The Holy See has Permanent Observer status with several international organizations (such as the UN, WTO, FAO and UNESCO), and is a member of others.  As well as less formal lobbying activity, it is continually making speeches, statements and interventions in resolutions.  A typical headline reads: “This week has seen several interventions by the Vatican delegation to the World Health Organization’s key decision making body.” 
1. "Concordat", Catholic Encyclopedia, 1908. http://www.newadvent.org/cathen/04196a.htm
2. By early in 2012 there were concordats with 42 states. "Former ambassador dismisses move to change Spain's accord with Vatican", Catholic News Agency, 2012-02-20. http://www.catholicnewsagency.com/news/former-ambassador-dismisses-move-to-change-spains-accord-with-vatican/ There were three more during the course of that year, at least two in 2014, at least three in 2015, (counting the tactfully named Avenant with France), and three in 2016. "Note on the diplomatic relations of the Holy See, 09.01.2017", Holy See Press Office, 2017-01.09. http://press.vatican.va/content/salastampa/en/bollettino/pubblico/2017/01/09/170109b.html
3. "The numerous concordats concluded towards the middle of the 19th century with several of the South American republics either have not come into force or have been denounced and replaced by a more or less pacific modus vivendi."
"19th-century concordats", Volume 6, Page 834 of the 1911 Encyclopedia Britannica.
4. Gianni Cardinale, "Diplomacy between the cross and the crescent", [subtitle: "Almost all the Islamic countries have an apostolic nuncio already. Ten Muslim States, however, are missing from the list. For the moment"], 30 Days, October 2006. http://www.30giorni.it/us/articolo.asp?id=11745
5. "Vatican and United Arab Emirates sign diplomatic agreement", Vatican Radio, 2016-09-15. http://en.radiovaticana.va/news/2016/09/15/vatican_and_united_arab_emirates_sign_diplomatic_agreement/1258333
6. "Vatican and Arab League sign agreement to promote peace and dialogue", 2009-04-24
Canonical ID: 09VATICAN60_a https://wikileaks.org/plusd/cables/09VATICAN60_a.html
7. "Pope Francis' Address to Diplomatic Corps", Zenit, 2014-01-13. http://www.zenit.org/en/articles/pope-francis-address-to-diplomatic-corps
8. "Vatican Ratifies Agreement With Montenegro", Balkan Insight, 2012-06-22.
9. Roman Catholic Church can establish and run schools in Serbia, InSerbia News, 2015-01-15 http://inserbia.info/today/2015/01/roman-catholic-church-can-establish-and-run-schools-in-serbia/
10. "Number of Priests Worldwide Continues Steady Increase", Zenit, 2012-03-12. http://www.zenit.org/article-34441?l=english
11. Cooperation Agreement between the Organization of African Unity (OAU) and the Holy See, 2000-10-19.
12. "Pope Receives President of Gabon", Vatican Information Service, 2009-12-10.
13. "Holy See And Mozambique Ratify Their 2011 Agreement", Vatican Information Service, 2012-03-15. http://visnews-en.blogspot.no/2012/03/holy-see-and-mozambique-ratify-their.html
14. "Agreement between the Holy See and Burundi", Vatican Information Service, 2012-11-08. http://visnews-en.blogspot.no/2012/11/agreement-between-holy-see-and-republic.html
"Agreement Ratified Between Holy See And Republic Of Burundi", Vatican Information Service, 2014-03-03. http://visnews-en.blogspot.no/2014/03/agreement-ratified-between-holy-see-and.html
15. "Holy See signs agreement with Equatorial Guinea", Vatican Radio, 2012-10-13. http://en.radiovaticana.va/articolo.asp?c=629477
"President Obiang Of Equatorial Guinea Meets With Pope", Yahoo News, 2013-10-31.
16. "Accord between Holy See and Cape Verde", News.VA, 2013-06-11. http://www.news.va/en/news/accord-between-holy-see-and-cape-verde
"Ratification of the Agreement between Holy See and Cape Verde", VIS, 2014-04-03. http://www.news.va/en/news/ratification-of-the-agreement-between-the-holy-see
17. "Agreement between the Holy See and the Republic of Chad on the Legal Status of the Catholic Church", Vatican Information Service, 2013-11-07. http://visnews-en.blogspot.no/2013/11/agreement-between-holy-see-and-republic.html
18. "Cameroon, Holy See Sign Agreement On Legal Status", All Africa, 2014-01-13. http://allafrica.com/stories/201401140674.html
19. "Holy See signs framework agreement with DRC", Vatican Radio, 2016-05-20. http://en.radiovaticana.va/news/2016/05/20/holy_see_signs_framework_agreement_with_drc/1231258
20. "Agreement between the Holy See and the Central African Republic, 07.09.2016", Holy See Press Office. http://press.vatican.va/content/salastampa/en/bollettino/pubblico/2016/09/07/160907c.html
21. "Signing of Framework Agreement between the Holy See and the Republic of Benin, 22.10.2016", Holy See Press Office. http://press.vatican.va/content/salastampa/en/bollettino/pubblico/2016/10/22/161022d.html
22. "Vatican Secretary of State signs diplomatic accord with Republic of Congo", Catholic Culture, 2017-02-03. http://www.catholicculture.org/news/headlines/index.cfm?storyid=30667
23. "Africa’s Catholic population has grown by 238 per cent since 1980", Catholic Herald, 2015-06-03. http://www.catholicherald.co.uk/news/2015/06/03/africas-catholic-population-has-grown-by-238-per-cent-since-1980/
24. Philip Jenkins, The Next Christendom: The Coming of Global Christianity, 2011, p. 73.
25. Adam Nossiter, "Church Helps Fill a Void in Africa", New York Times, 2013-02-23. http://www.nytimes.com/2013/02/24/world/africa/catholic-church-fills-growing-void-in-africa.html
26. Edward Pentin, "The Pope as Diplomat", Foreign Affairs, 2013-02-27. http://www.foreignaffairs.com/articles/139031/edward-pentin/the-pope-as-diploma
27. "Lawmakers conditionally consent to qualifications recognition by Vatican", Taipei Times, 2012-06-08. http://www.taipeitimes.com/News/taiwan/archives/2012/06/08/2003534815
28. "Beijing, Vatican reach initial accord on appointment of bishops, Hong Kong cardinal says", South Chaina Morning Post, 2016-08-05. http://www.scmp.com/news/hong-kong/politics/article/1999710/beijing-vatican-reach-initial-accord-appointment-bishops
(This quotes Cardinal John Tong Hon's article published in the the weekly diocese publication Kung Kao Po, 2016-08-04.)
29. "Participation in International Organizations", Vatican City State. http://www.vaticanstate.va/content/vaticanstate/en/stato-e-governo/rapporti-internazionali/partecipazioni-ad-organizzazioni-internazionali.html
30. Holy See Mission to the United Nations in Geneva, [look under "Sector"] http://holyseemissiongeneva.org/index.php?option=com_content&view=article&id=14368:66th-world-health-assembly-may-2013&catid=68:health&Itemid=90
31. "Vatican supports new direction on health for World Health Organization", Catholics in Healthcare, 2013-05-25 http://catholicsinhealthcare.wordpress.com/2013/05/25/vatican-proposes-new-direction-on-health-for-world-health-organization/