Why did the Don Cossacks settle along the middle and lower Don River?

The Don Cossacks settled along the middle and lower Don River primarily as a result of fleeing from serfdom in Poland, Lithuania, and Muscovy during the late 15th century.1

Seeking freedom and independence, these individuals migrated to the Don region, where they established self-governing, autonomous military communities. By the 16th century, these groups had firmly entrenched themselves along the river's middle and lower courses. While they initially maintained a high degree of independence, they eventually entered into a complex relationship with the Russian Empire, serving as frontier defenders in exchange for certain privileges and a degree of autonomy, though they were gradually brought under tsarist control over the following centuries.12