Link for this series in the description, and this is set before the Archie reboot preceding the Worlds Collide crossover

The echidnas experimented on Thrash’s race and turned them into mutants, so he wanted revenge.

@@DarkKnight-by7ql dang So are the echidnas really extinct in the comics or are they in hiding? Also Thrash looks kinda like an echidna Do they ever say what his race really Is? Thanks💯💯💯

chris S. Thrash is some sort of Tasmanian Devil. We never really find out for sure what happened to the echidnas. When we see them last, their city is being invaded by Eggman forces. The echidnas become desperate for survival, so Thrash opens a large warp ring to an unknown location, promising them they will be safe. The echidnas quickly decide that’s their best option, oblivious to Thrash’s motives. When Knuckles finally makes it to the city, it’s too late. Many of the buildings are in ruins and there’s no trace of the people. He later confronts Thrash, demanding their return. But Thrash coldly responds that it’s too late. Knuckles fights him for a while, while Thrash explains why he did whatever he did, showing no remorse. Knuckles is upset because those echidnas were some of the last of his race. Thrash later escapes during the conflict. Like I said, we never actually see what happens to them, and it’s never confirmed. But it’s heavily implied that the echidnas were all killed, including Knuckles’ girlfriend/closest friend.

@@DarkKnight-by7ql From what I've read, they were sent to the Twilight Cage. The place in Sonic Chronicles: The Dark Brotherhood.