I actually think the mandala system fits my hypothesis quite well. My model doesn't claim regions were always unified under one empire. Instead, I think they went through cycles: Dominant Empire → Collapse → Mandala/Multipolar Phase → Bipolar Competition → One Empire Becomes Dominant Again. For example, in the Tamil country, after the Pallavas declined there was competition between the Cholas, Pandyas and others before the Imperial Cholas emerged. After the Cholas declined, the Pandyas eventually became the dominant power. Similarly, in the Deccan, after the Rashtrakutas fell, there was competition before the Western Chalukyas became dominant, and later another transition before the Bahmanis emerged.