Tammany Hall had plenty of crooks, and no doubt was happy to make terms with robber barons. But it was far from consisting of classic "robber barons".

Tammany Hall was part of a world which started with the Robber Barons and ended with the Bosses distributing the funds to the ward heelers. Jay Gould funded Tammany Hall. Sure, it was also self-perpetuating corruption, but it had linkage.

It didn't consist "of" robber barons. It was a tool they used when it suited them. I call that cronyism.