For 10 points, identify this leader succeeded by his son Ogedai and grandson Kublai, who unified the Mongol empire.
This ruler sent a delegation of ambassadors to Ala ad-Din Muhammad, who shaved and beheaded all but one member. In response, this man attacked the Khwarezmian Empire with a force of twenty tumens. His rise to power began when he offered allegiance to the Kerait leader Toghrul. Later, due to the influence of Toghrul's son Senggum, Toghrul betrayed this leader for Jamuqa and was killed by a group of Naiman soldiers. For 10 points, identify this leader succeeded by his son Ogedai and grandson Kublai, who unified the Mongol empire.
This ruler sent a delegation of ambassadors to Ala ad-Din Muhammad, who shaved and beheaded all but one member.
{Genghis} Khan [or {Temujin}; prompt on "Khan"]