What was the Kofun period like?

"Kofun" is the name for the tombs of the rulers (gouzoku) of the period.
While they came in various shapes, all were built of mounded earth, with clay sculptures (haniwa) of people and horses adorning the exterior of the tomb, and funerary goods such as weapons, mirrors, and personal ornaments enclosed with the body inside the interior stone chamber.
The Kofun period refers to the period from the fourth century to the seventh century when these tombs were actively built.
It is during this period that gradual unification under the Yamato polity took place.
In the beginning of the seventh century, Prince Shotoku (574-622) laid the foundations for the state by instituting the Kani Junikai (twelve grades of cap rank), a system of courtly ranks, and the Seventeen Article Constitution.
This was also the period when Chinese and Korean immigrants came to Japan and conveyed new technology in handicrafts, farming, and construction.