The colonization of Transylvania by ethnic Germans later collectively known as Transylvanian Saxons began under the reign of King Géza II of Hungary (1141–1162).^[48] For several consecutive centuries, the main task of these medieval German-speaking settlers (as that of the Szeklers for example in the east of Transylvania) was to defend the southern, southeastern, and northeastern borders of the then Kingdom of Hungary against foreign invaders stemming most notably from Central Asia and even far East Asia (e.g. Cumans, Pechenegs, Mongols, and Tatars). At the same time, the Saxons were also charged with developing agriculture and introducing Central European culture.^[49] Later on, the Saxons needed to further fortify both their rural and urban settlements against invading Ottomans (or against the invading and expanding Ottoman Empire). The Saxons in northeastern Transylvania were also in charge of mining. They can be perceived as being quite related to the Zipser Saxons from present-day Spiš (German: Zips), north-eastern Slovakia (as well as other historical regions of contemporary Romania, namely Maramureș and Bukovina) given the fact they are two of the oldest ethnic German groups in non-native German-speaking Central and Eastern Europe.^[50]

The first wave of settlement continued well until the end of the 13th century. Although the colonists came mostly from the western Holy Roman Empire and generally spoke Franconian dialectal varieties, they came to be collectively referred to as 'Saxons' because of Germans working for the royal Hungarian chancellery.^[51]

Organized settling continued with the arrival of the Teutonic Knights in Ţara Bârsei in 1211.^[52] They were granted the right to freely pass through "the land of the Székelys and the land of the Vlachs" in 1222. The knights tried to free themselves from the monarch's authority, thus King Andrew II expelled them from the region in 1225.^[53] Thereafter, the king appointed his heir, Béla,^[54] with the title of duke, to administer Transylvania. Duke Béla occupied Oltenia and set up a new province, the Banate of Severin, in the 1230s.^[55]