Did they enforce shariah law everywhere in the Islamic empire of the middle ages?

I under stand that the Islamic empire unlike the Roman empire wasn't unified under one central authority but was kind of a confederation of smaller Muslim kingdoms ruled by individual Caliphs. So I'm curious if all the Caliphs and Sultans etc. ruled their territory the same way, and how common it was that they would rule their country as per the guidelines of Shariah law (i'm thinking especially of Kingdoms that had a bunch of non-mulsims in it back in the middle ages, like the territory held by Turks and by the Moors in Spain).