In both eras, many colours were in use. Clothes were dyed, but houses as well and you name what more. The most difficult to get colours (dark ones) were also the most expensive ones. Think for example about purple, which during the Roman Era was the colour of the senators. The use of colours depended on the goal: one colour would have another meaning than the other one. Some people were obliged to use a specific colour because of their status. Colours were often made out of plants (roots, fruit, leaves but think as well about charcoal) and from minerals and metals (ochre red – iron). They often did not stay in shape that long as nowadays, but our colours are more based in chemistry then ever.