Castles in the early 800 BCE were very simple. Take several acres of land, build a home made of grasses, straw and mud on the highest point. Encircle the home with stones or barrier materials no taller than 4 ft or so. Walk out of a small gate down a dirt path to a second enclosed area where more stationary domesticated animals could be managed.
A larger area surrounded that where grazing animals were kept and people could live within the boundaries for protection. They were extended family, married children and or laborers.
From that point on, castles were built up and out, close to water and made of stone, brick, morter. Style was influenced by Security, Status, Region, Culture and Religion.