What network is DeFi on?

Excuse me, but I'm curious to know which network Decentralized Finance, or DeFi, primarily operates on. Is it Ethereum, given its dominance in the smart contract space and the numerous DeFi applications built on its blockchain? Or are there other prominent networks that DeFi projects have also taken root in? It would be insightful to understand the landscape of DeFi and the underlying infrastructure that supports its growth and innovation.