The LoongArch ISA is used on CPUs created by Loongson, who have internally created a ?loongarch64 port that they are aiming to turn into an architecture available from Debian.
References
Initial discussion: <b5a53692-592c-2e3d-a996-a8d6692f4eb1@loongson.cn>
Mailing list request: 989125
Documentation: https://loongson.github.io/LoongArch-Documentation/