What chains is dYdX on?

Could you elaborate on the blockchain networks that dYdX currently operates on? I'm curious to know if it's a cross-chain protocol or if it's primarily focused on a specific blockchain ecosystem. With the growing popularity of decentralized finance and the emergence of various blockchain networks, it's important to understand the platforms that innovative projects like dYdX leverage for their operations. Your insight into this aspect could be valuable for investors and enthusiasts alike.