Have a seating arrangement for sitting on the rug.
My classroom teacher has a rug that is divided into squares and each student has their own square to sit in. It alleviates a lot of problems because students are not arguing over where they want to sit or who they want to sit by. The students know where they are supposed to be and know they should not be moving outside of thier square. It also makes it easy to tell students to get to thier place. You just have to remind them to stay in thier square.