It’s assumed people started living in the surrounding of Ouderkerk on the Amstel in the 10th or 11th century. Ouderkerk is the oldest settlement in the surroundings. Around the year 1275, in the mouth of the Amstel a dam was built which is how they decided to name the city of Amster-dam. Amsterdam was rapidly growing due to the canals that were being built and the trading that occurred, so it became the capital city of this area.
History of Amstel River Countryside (Amstelland):