I know, when i say mongol i was refering to mongols, which is why i speicifically mentioned khan in the next sentence. The empire was bound to collapse when the grandson defeated his father and his army. What's an empire without a leader?
Sorry, I didn't see the word Khan there.
The caliphate you are talking about was a caliphate by name only. They were morons at that time. The moron king/caliphate of that time was messing with the khan's people for no reason. He had too much pride in himself. Khan was busy taking over china side of the world when this caliphate started sticking his hand in the bee's nest. Khan sent his diplomats to sort it out and this moron killed the diplomats too. So khan put his work on hold against the chinese and started towards Muslims. He killed 10 million muslims. It was the punishment for muslims who had abandoned islam and were nothing more than muslims by names. And Islam was almost wiped out. Then Allah guided the grandson of khan and made him a defense against the enemies and a beacon of light for islam. Indeed it is easy for Allah to destroy a nation and raise better nation that will obey Allah.
It was the Shah of Iran who started on the Mongols and killed their diplomats, not the Caliph. Genghis wanted good relations with the Iranians for the time, so he sent some diplomats to establish good relations. the Shah, knowing what happened to Genghis Khan's other allies, didn't want relations with such a person and had the diplomats killed. So in response, the Khan destroyed the country and slaughtered its inhabitants.
In fact the destroyer of Baghdad was Hulagu Khan, not Genghis Khan.
Genghis Khan's grandson did convert to Islam. However, he didn't attack his father as you claimed, or did he conquer back his lands. He did attack Hulagu Khan's empire, but certainly didn't reconquer the whole empire. He didn't really take much territory off him.