Who is Sirian Agents from Shikasta: Re, Colonised Planet 5: Personal, Psychological, Historical... and what is their importance?

Sirius and Canopus are the Sirian agents, who divide up Shikasta into two halves, Canopus taking the Northern hemisphere and Sirius taking the Southern hemisphere. The agents are primarily interested in genetic experiments on animals and other humanoid races, but when their experiments are complete, they often remove the species from the Shikasta and relocate them to another area. Sirius regularly keeps agents around on Shikasta, and he also helps Canopus defeat Shammat.