Why were ancient greek communities isolated from each other?

They were isolated because they were often far away from each other and were independent of each other because a united Greek state didn't exist, they were all independent city states. Many of them were also on islands that were inaccessible by normal means. Roads were not as developed because of the many islands and rivers and things like that, so they developed in isolation.

The answer is william henry harrison pursued and defeated british forces retreating into canada.