The initial phase of German settlement began in the mid-12th century with colonists travelling to what would become the Altland or Hermannstadt Provinz (Sibiu County), based around the city of Hermannstadt (Sibiu). Although the primary reason for Géza II's invitation was border defense with the Szeklers against invaders, Germans were also sought for their mining expertise and ability to develop the region's economy. Most colonists from this era came from Luxembourg and the Moselle River region.
A second phase of German settlement came during the early 13th century consisting of settlers primarily from the Rhineland, Southern Low Countries, and the Moselle region, with others from Thuringia, Bavaria, and even from France. A settlement in northeastern Transylvania was centered on the town Nösen, the later Bistritz (Bistriţa), located on the Bistriţa River. The surrounding area became known as the Nösnerland. Continued immigration from the Empire expanded the area of the Saxons further to the east. Daughter settlements from the Hermannstadt region spread into the Hârtibaciu River Valley (Harbachtal) and to the feet of the Cibin(Zibin) and Sebeş (Mühlbacher) mountains. The latter region, centered on the city of Mühlbach (Sebeş) was known as the Unterwald. To the north of Hermannstadt was settled the Weinland near Mediasch (Mediaş).
In 1211 King Andrew II of Hungary invited the Teutonic Knights to settle and defend the Burzenland in the southeastern corner of Transylvania. To guard the mountain passes of the Carpathians (Karpaten) against the Cumans, the knights constructed numerous castles and towns, including the major city of Kronstadt (Braşov). Colonization in the Burzenland region consisted mostly of settlers from the Altland. Alarmed by the knights' rapidly expanding power, in 1225 Andrew II expelled the Order which henceforth relocated to Prussia in 1226, although the colonists remained in the Burzenland.
The Kingdom of Hungary's medieval eastern borders were therefore defended in the northeast by the Nösnerland Saxons, in the east by the non-German Szeklers, in the southeast by the castles built by the Teutonic Knights and Burzenland Saxons, and in the south by the Altland Saxons.