Mahabharat is "itihas" or a book of history. It is neither a book of religion (which is Veda) nor of law (which is Manusmriti).
Mahabharat war, as the name suggests, happened in Bharat - a nation which contained 18 "janapad" or states, each ruled by a "Mandlik raja".
"Sindhu-desh" (Harappa and...