Masuria and the Masurian Lakes Plateau are known in Polish as Kraina Tysiąca Jezior, and in German as Land der Tausend Seen which means the same as (the) "land of a thousand lakes". As in other parts of post 1945 northern Poland, from Pomerania on Oder Odra river to Vistula (Wisła) river, one continuous stretch of lakes makes it a beautiful holiday location. These lakes were ground out of the land by glaciers during the ice age, when ice covered north-eastern Europe. By 10,000 BC this ice started to melt. Great geological changes took place and even in the last 500 years the maps showing the lagoons and peninsulas on the Baltic Sea have greatly altered in appearance.

In the southern part of the region, the ancient Prussian Sudovia and Galindia lands, wilderness areas survived for longer than in most of Europe. The deep forests in these territories made it possible for moose, aurochs, bears and many other mammals to survive. During the Baltic or Northern Crusades of the 13th century the native Prussian population also had the chance to survive in the remaining wilderness areas against the onslaught of the Teutonic Knights (of German origin) and other crusaders from elsewhere in Europe (mainly from Germany), who were sent by the pope to baptize by conquest of the land and conversion of the native population to Christianity. The south-eastern part of Prussia was getting penetrated by Poles.

Polish settlers, mainly from Masovia, so called Mazur, began to arrive following the Teutonic Order's conquest of the area. German, French, Flemish, Danish, Dutch and Norwegian colonists entered the area shortly afterward, founding numerous cities and towns. The occasional assumption, that by the 15th century, the original Prussian population was exterminated, is proven false, by many individual land and people records kept of Altpreussische Urkunden (trans. Old prussian documents). The Prussians language however suffered a decline, because Low German was the official language, from which the Ostpreussisches Platt (East Prussian Platt) , unique to this region developed.

In Masuria - the southern part of East Prussia Polish language dominated due to the many settlers from Masovia. In the Second Treaty of Thorn (1466) the Teutonic Order acknowledged the overlordship of the Polish crown. Since 1525 Masuria (with the exception of Warmia) has had a mostly Protestant population. The cities remained centres of German and Polish speakers, however the cities usualy had as a requirement to become a burgher (citizen) 'to be of German tongue'. The most ancient Old Prussian language survived in parts of the countryside until the early 18th century.

In 1656 the Ducal part of Masuria was devastated during the Deluge, when it was raided by Tartars and Poles. In 1708 some one third of population died during the Plague.

Losses in population were compensated by migration from Scottland, Salzburg, France and Poland, Lithuania and other refugees, including Polish Arians (Polish brethren), expelled from Poland in 1657. The last such group were the Russian Filipons in 1830.

The name Masuria began to be used officially after new administrative reforms in Prussia after 1818.

Germanisation was slowly and mainly done by education: in 1872 Polish language was removed from schools. In 1890 143,397 of Masurians gave German as their language (either first or second), 152,186 Polish, and 94,961 Masurian. In 1910, the German language was given by 197,060, Polish by 30,121, and Masurian by 171,413. In 1925, only 40,869 people gave Masurian as their native tongue and only 2,297 gave Polish.

After WW II, the League of Nations held a plebiscite in 1920 as to whether the people of the two southern districts of East Prussia wanted to remain within East Prussia or to join the state of Poland: 97.5% voted to remain with East Prussia, an outcome at least in this magnitude somewhat to the surprise of Polish organisations in Masuria.