Here is a relatively short presentation: https://www.youtube.com/live/3us83qvzopM and the slides.

There’s this back story about the “LoongArch instruction system, a RISC ISA that blends ideas from MIPS and RISC-V”. The article says it is MIPS-compatible and even runs the same Linux code [Loongson’s] old MIPS-based CPUs did. Why not just use RISC-V? MIPS is licensed from the USA. I guess they have a lot of legacy people at Loongson.