How must we understand these cultural practices of certain tribes?Through out India Navaratri festivals are going on. But in central India a particular tribe of Gonds regard Mahisasur as their Great King who was benevelont. And aryans under Lord Durga killed him. They still rever him as their ancestoral head.
The above Legen is not in isolation but through out India there are stories like these glorifying those whom Hinduism regard as demons. For example Ravana is regarded as hero by some tribes of Tamil Nadu and Sri Lanka. Their justification is Ravan as any brother was enraged by Ram's action of insulting his sister and hence kidnapped Sita to make Ram understand his pain. He had no bad intention and it is corrobrated by his protection to Sita from all harms until the his death.
How do you view these legends. They severely question the authority of Vedas to show them in poor light.