Answer:
The Mongols controlled many former Slavic territories from the 1200s to 1400s.
Explanation:
From the 1200s to the 1400s, a huge empire arose from the steppes of Mongolia. Initially led by Genghis Khan, whi managed to unite the Mongols, the Mongols had great success in Eastern Asia, Central Asia, and the Middle East. His sons and later nephews continued the expansion, reaching Europe, until the fall of the empire because of internal conflicts and disagreements among the leaders.
Most of the territory that was conquered in Europe was predominantly inhabited by Slavic people which had their own kingdoms until being invaded. The Mongols managed to conquer or control the territories of most of what is now the European part of Russia, Ukraine, Belarus, and the eastern part of Poland. The Mongols actually managed to conquer territories in Europe with relative ease, and the only thing that stopped them in their military campaigns was the internal problems that they had at this point, otherwise, they would have most probably managed to reach the Atlantic coast without any particular problem.