Question

was the Mongol empire under Genghis Khan was larger than the later Mongol empire under his grandson Kublai Khan?

Answer 1

Generally speaking, the Mongols controlled a larger area when Kublai ruled than when Genghis ruled. But the empire had started to break apart. Mongol rule went from Korea to Hungary and included Iran, parts of India and south east Asia. But Kublai concentrated on the east. He proclaimed himself Emperor of China and took southern China from the Song dynasty. Kublai became more and more Chinese and cared less and less about the western part of the empire which was ruled by other sons and grandsons of Genghis.