Final answer:
The Mamluk sultans treated Syrian Arab rebels more leniently because they needed their help to fight against external threats like the Mongols and Ottomans, whereas rebellious Arab Bedouins in Egypt faced severe punishments.
Step-by-step explanation:
The Mamluk sultans treated rebellious Syrian Arabs more leniently than they did the rebellious Arab Bedouins in Egypt for strategic reasons. The Bedouins faced severe punishments for their revolts, including execution and enslavement, with their leaders' heads displayed as warnings. In contrast, the Syrian Arabs were less harshly punished because their assistance was crucial in combating threats from external forces like the Mongols and the Ottomans. Therefore, the Mamluk rulers pursued a more diplomatic approach with Syrian rebels to ensure their cooperation against common enemies.