In the Treaty of Salynas, Lithuania cedes Samogitia to the Teutonic Knights.

The Treaty of Salynas was a peace treaty signed on 12 October 1398 by Vytautas the Great, the Grand Duke of Lithuania, and Konrad von Jungingen, the Grand Master of the Teutonic Knights. It was signed on an islet of the Neman River, probably between Kulautuva and the mouth of the Nevėžis River. It was the third time, after the Treaty of Königsberg (1384) and Treaty of Lyck (1390), that Vytautas promised Samogitia to the Knights. The territory was important to the Knights as it physically separated the Teutonic Knights in Prussia from its branch in Livonia. It was the first time that the Knights and Vytautas attempted to enforce the cession of Samogitia. However, it did not solve the territorial disputes over Samogitia and they dragged on until the Treaty of Melno in 1422.

Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, Poland to the south, and the Russian semi-exclave of Kaliningrad Oblast to the southwest, with a maritime border with Sweden to the west. Lithuania covers an area of 65,300 km² (25,200 sq mi), with a population of 2.9 million. Its capital and largest city is Vilnius; other major cities include Kaunas, Klaipėda, Šiauliai and Panevėžys. Lithuanians are the titular nation, belong to the ethnolinguistic group of Balts, and speak Lithuanian.

Samogitia, often known by its Lithuanian name Žemaitija is one of the five cultural regions of Lithuania and formerly one of the two core administrative divisions of the Grand Duchy of Lithuania alongside Lithuania proper.

The Teutonic Order is a Catholic religious institution founded as a military society c. 1190 in Acre, Kingdom of Jerusalem. The Order of Brothers of the German House of Saint Mary in Jerusalem was formed to aid Christians on their pilgrimages to the Holy Land and to establish hospitals. Its members have commonly been known as the Teutonic Knights, having historically served as a crusading military order for supporting Catholic rule in the Holy Land and the Northern Crusades during the Middle Ages, as well as supplying military protection for Catholics in Eastern Europe.