"The collapse of the Soviet Union in 1991 left state-owned industries open to privatization. Hoffman says a few men captured companies dealing in natural resources.

"Timber, diamonds, oil, you name it," Hoffman said. He added that the entrepreneurs were "these young hustlers, kids who had not been part of the Communist Party. And seven of them became prominent businessmen by glomming on to these big valuable assets."

'
"Putin's seemingly populist moves consolidated his own power.

Oligarchs who supported independent media were the first to go. The few who remained "were cowed into staying out of Putin's way.

Furthermore, as time went by, Putin didn't change the system. What he did was he installed his own people as oligarchs. He changed the guy sitting in this chairs, but he didn't change the chairs."

More at the link.... it's not a long article, but it's real history about Trump's mentor.