Neighbourhoods in very old cities often grouped certain people together. Ethnic neighbourhoods were important in many old cities. They are still common in cities today. Economic specialists, including craft makers, merchants, and others, could be grouped together in neighbourhoods. There were also neighbourhoods based around certain religions. One important part to neighbourhood being different from each other and their people getting along well was how people moved from rural areas to the cities. This was always happening in old cities. The people moving to the cities often moved in with relatives and people they knew from before moving to the city.