how do you take over grey cities on the map ?

[Conker]

been on google all day and I can't figure it out ?

[-=Prepper_Jack=-]

Colonize. You need 10 pop in a province that is either adjacent to it by land, or within the same sea zone.

[VladK02]

click on grey city, there is a button Colonize in its window. your cities can colonize adjacent grey areas once a year, IF your culture and religion are dominant and you have 10 pop.

Or play as rome, they have a mid-game ability called build fort. Send legion into grey area, click button, a city pops up, with a fortress and all. There is a cost but hey, its rome's variant of colonists.

Migratory tribes are easiest. You can pack up your existing city, and every pop in it turns into a settler. Those settlers can colonize empty grey areas. Minimum number of settlers is 3, and if local grey city has 5- or 6 pops or something, number ofyour settlers has to match number of locals. So, this is what you do as a tiny migratory tribe at start of game - send all your pops into once mega-city at the start of the game, pick it up, turn them into 30 or so settlers, go into empty province somwhere - ireland, or poland, settle those areas.