Perhaps the oldest era in the recorded history of Japan, the Kofun period began in the 3rd century. Though Japanese tribal leaders remained in close economic and political contact with Korea during this period, they also increasingly consolidated their power. It was a critical stage in the evolution of a unified Japanese state. The introduction of Buddhism in 538 CE marked the start of a new and different era. The Kofun period is especially known for the building of what distinctive structures? Discuss