WHAT?!?!?!? The Ki???
No, I didn’t think so, because in the Galactic Timeline at the end of The Rookie, it states
“1967 Collector gate built on Ki Homeworld. Ki race subjugated.
1998 Collector orbital arrives on Earth.
2008 Collectors fail in multiple attempts to invade Earth.
2009 Ki uprising against Collector homeworld.”
I took that to mean Earth was not the only planet they attempted to build gates and take over.