Question: In what year did the line from which Premyslaw II come from become extinct?

Context articles: Nassau Family Pact
Extinct Birds
Poukai
Glyptotherium
List of recently extinct mammals
Przemysław II, Duke of Cieszyn
Endangered language
Succession to Peerages Bill (2015–2016)
Disappearing blonde gene
Duchy of Teschen

The Nassau Family Pact was a mutual pact of inheritance and succession made in 1783 by princes of the old European noble and sovereign family of Nassau.
 It confirmed that Salic Law was to operate in favor of all the agnatic lines of the family, specifically the two senior surviving lines which had originated in the Middle Ages, the Walramian and the Ottonian.
 The pact chiefly provided that in case of one of these lines becoming extinct, the other would succeed in its hereditary Nassau lands ("the main concept of the pact was that if either the Ottonian or Walramian male line would become extinct the other line would succeed").
Extinct Birds (complete title: Extinct birds.
 An attempt to unite in one volume a short account of those Birds which have become extinct in historical times—that is, within the last six or seven hundred years.
 To which are added a few which still exist, but are on the verge of extinction.)
 is a book by Walter Rothschild which covers globally extinct and rare birds as well as hypothetical extinct species which include bird taxa whose existence is only based on written or oral reports or on paintings.
 The accounts of the extinct bird taxa are based on Rothschild's lecture "On extinct and vanishing birds" published in the Proceedings of the 4th International Ornithological Congress 1905 in London.
In Māori mythology, the pouakai or poukai is a monstrous bird.
 In some of these legends pouakai kill and eat humans.
 The myth may refer to the real but now extinct Haast's eagle: a bird of massive size and strength, believed to have hunted moa (which could weigh up to 230 kg ), and which had the capability to possibly kill humans.
 Haast's eagles did not become extinct until around one hundred years after the arrival of the Māori, and was thought to have become extinct due to overhunting by the Māori, and loss of natural habitat.
Glyptotherium is an extinct genus of glyptodont, a group of extinct mammals related to the armadillos living from 4.1 to 1.5 million years ago (AEO).
 The genus is considered an example of North American megafauna, of which most have become extinct.
 "Glyptotherium" may have been wiped out by climate change or human interference.
Recently extinct mammals are any mammal that went extinct since the year 1500 C. E., as defined by the International Union for Conservation of Nature (IUCN).
 Strong scientific records show that since the year 1500 roughly 80 mammal species have become extinct.
Przemysław II of Cieszyn, also known as Przemko II (Polish: Przemysław II cieszyński , Czech: Přemysl II.
 Těšínský , German: Przemislaus II.
 von Teschen ; 1422/25 – 18 March 1477), was a Duke of Cieszyn (Teschen, Těšín) from 1431, ruler over Bielsko and Skoczów (from 1442), Duke of half of both Duchy of Głogów (Glogau, Hlohov) and Duchy of Ścinawa from 1460 and from 1468 sole ruler over Cieszyn.
An endangered or moribund language is a language that is at risk of falling out of use as its speakers die out or shift to speaking another language.
 Language loss occurs when the language has no more native speakers and becomes a "dead language".
 If no one can speak the language at all, it becomes an "extinct language".
 A dead language may still be studied through recordings or writings, but it is still dead or extinct unless there are fluent speakers.
 Although languages have always become extinct throughout human history, they are currently dying at an accelerated rate because of globalization and neocolonialism.
The Succession to Peerages Bill was a bill intended to allow daughters of peers to inherit a peerage if the peerage would otherwise become extinct due to the absence of a male heir.
 It would have applied retrospectively to peerages that had become extinct since the start of the reign of Queen Elizabeth II in 1952.
The disappearing blonde gene was a hoax about how a scientific study had estimated that natural blonds would become extinct, repeated as fact in reputable media such as the BBC and "The Sunday Times" between 2002 and 2006.
 Claims that blond hair would disappear have been made since 1865.
 According to the erroneous reports, someone, for instance the World Health Organization (WHO), published a report claiming that people with blond hair "will become extinct by 2202".
The Duchy of Teschen (German: "Herzogtum Teschen" ), also Duchy of Cieszyn (Polish: "Księstwo Cieszyńskie" ) or Duchy of Těšín (Czech: "Těšínské knížectví" , was one of the Duchies of Silesia centered on Cieszyn ("Teschen") in Upper Silesia.
 It was split off the Silesian Duchy of Opole and Racibórz in 1281 during the feudal division of Poland and was ruled by Silesian dukes of the Piast dynasty from 1290 until the line became extinct with the death of Duchess Elizabeth Lucretia in 1653.