Why did Genghis Khan feel the need to fragment the Mongol tribes into new social and military groupings?
Genghis Khan fragmented the Mongol tribes into new social and military groupings to systematically erase old tribal identities. In the earlier system, the clan and tribe coexisted within decimal units, which could lead to divided loyalties. By dividing old tribal groupings and distributing their members into new military units, Genghis Khan ensured that the largest unit (tuman) now included people from a variety of different tribes and clans.
This measure altered the old steppe social order by integrating different lineages and clans. It provided them with a new identity derived from Genghis Khan, the progenitor, rather than their previous tribal affiliations. This created a unified and loyal military force under his central command.
Explanation
The answer draws directly from the textbook context which explains Genghis Khan's policy of dismantling old tribal structures. The key points are: (1) erasing old tribal identities, (2) breaking the coexistence of clan and tribe within units, (3) creating mixed military units, and (4) establishing a new identity centered on loyalty to Genghis Khan. This was crucial for consolidating his hold over diverse Mongol tribes and preventing the fragmentation that had plagued earlier confederacies.