The presence of the German ore miners, known locally as "sasi" (саси, Saxons), cannot be accurately dated. Some researchers estimate their arrival in Chiprovtsi to be in the mid-14th century, the time of the last Bulgarian emperors, while others claim they reached the town during the early Ottoman rule of Bulgaria. Their exact number and place of origin are also vague, although the German miners were widely recruited as specialists in medieval Wallachia, Transylvania and Serbia. In Chiprovtsi, they are thought to have arrived as a single group of about 50–60 people with their families. They were probably recruited through special contracts and likely received some privileges compared to the native Bulgarian population. In Chiprovtsi's mines, they served as technicians and overseers, contributing to the technological progress of mining in the region. They were, however, gradually assimilated by the local Bulgarians by the mid-15th century, as indicated by German names with Slavic suffixes in the population registers. The Germans left behind the name of one of the neighbourhoods, still known as the "Saxon" neighbourhood in the 17th century, and Roman Catholicism as the dominant religion in the town.