Lith′ua′nia, the former name of a large tract of land between Poland and Prussia, which in the middle ages constituted an independent realm closely connected with that of Poland.  Now it belongs to Russia, with the exception of a small part in the East Prussian district of Gumbinnen.  It is a flat, low country, covered to a great extent with sand-heaths, marshes and forests.  The principal rivers are the Dnieper, Duna, Beresina, Pripet and Niemen.  The chief exports are grain, hemp, flax, honey, timber, cattle and horses.  The inhabitants are chiefly Lithuanians, Poles, Russians, Tartars and Jews.  Lithuania, because it had no natural boundaries, was frequently invaded, but, after being long tributary to various neighboring Russian principalities, it recovered its independence about the 12th century, only to become involved in a struggle with the Knight sword-bearers and the Teutonic Order who converted them to Christianity.  The people had no central government until the latter part of the middle ages.  Ryngold, a partly mythical chief of the early part of the 13th century, is thought to have begun a stable government.  Ryngold’s son Mindog, a purely historical character, reigned over Lithuania until about 1263.  Gedimen (1315–1340) made Lithuania a powerful state by the conquest of Volhynia and Kilo, which had belonged to Russia.  In 1386 Jagello, grandson of Gedimen, grand prince of Lithuania, married Hedwig, the daughter of Louis the Great of Poland, and became King of Poland with which he united Lithuania; he also converted his hereditary subjects to Christianity.  After Jagello, for 100 years Lithuania and Poland had separate rulers, although somewhat united politically.  From 1501 they had a common ruler; in 1569 the Diet of Lublin decreed the permanent union of Poland and Lithuania into one commonwealth to be governed by an elective king.  From this time the history of Lithuania is that of Poland.  At its greatest power, in the 14th century, Lithuania extended from the Baltic Sea to the Black Sea and from the northern Bug River to the Don.  In 1772 it consisted of the palatinates of Wilna, Troki, Novogrodek, Brzesc, Vitebsk, Polotzk and Matiolov and the duchy of Samogritia.  All are included in the Russian governments of Wilna, Mohileo, Minsk and Suwalki, an area of about 100,000 square miles.  Lithuanian, a branch of Lettic, is spoken in parts of East Prussia, in Samogritia and in Lithuania proper.