[Hunter]

Originally Posted by Mr. Johnny 5

Spoiler for answer:

The 3rd Kazekage was considred the most powerful Kazekage in Suna (Sand's) History. The 3rd Kazekage was the previous host of the Shukaku...Gaara was most likely the 2nd host. I believe that Chiyo-baa was also part of the "first" ritual of the 3rd Kazekage.

Spoiler:

He wasn't a host for Shukaku, he used the jutsu of the previous host as inspiration to his iron sand.