Vlachs (English:  or , or rarely ) is a historical term and exonym used for the Eastern Romance-speaking peoples especially in the Balkans. The term also became a synonym in the Balkans for the social category of shepherds, and was also used for non-Romance-speaking peoples, in recent times in the western Balkans derogatively. Apart from the Romanians and Moldovans, there are indigenous Romance-speaking groups in Greece, Albania and Macedonia, such as the Aromanians and Megleno-Romanians. "Vlachs" were initially identified and described during the 11th century by George Kedrenos.

In 1213 an army of Romans (Vlachs), Transylvanian Saxons, and Pechenegs, led by Ioachim of Sibiu, attacked the Bulgars and Cumans from Vidin. After this, all Hungarian battles in the Carpathian region were supported by Romance-speaking soldiers from Transylvania.  At the end of the 13th century, during the reign of Ladislaus the Cuman, Simon de Keza wrote about the Blacki people and placed them in Pannonia with the Huns. Archaeological discoveries indicate that Transylvania was gradually settled by the Magyars, and the last region defended by the Vlachs and Pechenegs (until 1200) was between the Olt River and the Carpathians.  Shortly after the fall of the Olt region, a church was built at the Carta Monastery and Catholic German-speaking settlers from Rhineland and Mosel Valley (known as Transylvanian Saxons) began to settle in the Orthodox region. In the Diploma Andreanum issued by King Andrew II of Hungary in 1224, "silva blacorum et bissenorum" was given to the settlers. The Orthodox Vlachs spread further northward along the Carpathians to Poland, Slovakia, and Moravia and were granted autonomy under Ius Vlachonicum (Walachian law).  In 1285 Ladislaus the Cuman fought the Tatars and Cumans, arriving with his troops at the Moldova River. A town, Baia (near the said river), was documented in 1300 as settled by the Transylvanian Saxons (see also Foundation of Moldavia). In 1290 Ladislaus the Cuman was assassinated; the new Hungarian king allegedly drove voivode Radu Negru and his people across the Carpathians, where they formed Wallachia along with its first capital Campulung (see also Foundation of Wallachia).

Answer the following question by taking a quote from the article: Can you tell me what led to this?
At the end of the 13th century, during the reign of Ladislaus the Cuman, Simon de Keza wrote about the Blacki people and placed them in Pannonia with the Huns.