Recruitment Viewer, MIC and Government questions

[Frtigern]

Using the Recruitment Viewer I am given two different complexes or MICs, numbered 7 and 21, and levels 1-5 that show me what units are recruitable. I have no idea what the number's 7 and 21 represent. Is 7 the factional MIC and 21 the regional MIC? Also is complex 21 or the regional MIC only allowed in certain governments like type 3 or 4, and complex 7 or the factional MIC only allowed in governments 1 or 2? Are complex 21, or regional MICs recruitment rosters unavailable to type 1 and 2 governments?

I am wondering because I am playing a Getai campaign and am looking for good expansion options worthy of assimilating for other culture's unique units. I am planning to go north to the Baltic and taking the Amber Route and am wondering if I must build type 4 governments all the way up, because Client Rulers are expensive and sometimes undesirable characters and sometimes I have a glut of good family members that I want to give a province to, without being interlopers.

Thank you