Let's say one of your neighbour's got completely bamboozled by Shaka. Later in the game, you destroy Shaka, and liberate your defeated neighbour's capital. This neighbour was guarded at the time he was destroyed, but when he is brought back to life from complete annihilation, he is still guarded. Why should a civilization, that only exists because of your kindness, still be angry at you for your past offences? I believe that a civilization that is brought back from annihilation should forget all past offences, and start anew. That civilization should only remember the good things that happened in the past, and it definitely shouldn't nitpick over past quarrels when it owes its own existance to you!