Emphasizing on the diversity of topography in relation to the Petchburi River which contains high mountains with thick forest on the west, flat terrain along the river and seaside land on the east, and on the diversity of water from fresh to brackish water which transforms to salt water while running down to the Gulf of Thailand, we can notice that the topography and natural resources on the west side and east side are not familiar with Siam Thai people who have settled down in this area for such a long time. In reality, there are various ethnic groups settling down in Petchburi from generation to generation--some settled long time ago, some newly migrated for more fertile lands and some migrated for escaping from wars. Each ethnic group selected their settlement from their familiarity to the context, culture and way of living. For example, the Chinese ethnics chose their settlement on the sea side land with the occupation of fishery and ark shell collectors. The Karen who migrated from Myanmar preferred the high mountain and thick forest on the west which was quite similar to their anchestor’s settlement in the past. The Thai with their experience in wet rice fields and fruit orchards always have their priority for settlement in the flat terrain along the water resource.