Answer:
400: On the plains of what someday will be called the United States, the bow and arrow is replacing the spear, the bow and arrow giving hunters and warriors a greater striking distance. Bantu speaking people have been migrating through the territory of other peoples and they have reached the southern tip of the African continent.
300 Christians across empire are about ten percent of the population. In the eastern half of the empire they are twenty or more percent of the population. North Africa had become largely Christian, the result of Christian evangelists having learned the Coptic and Berber languages.
200 Power in China has passed to warlords, and respect for Confucianism fades with the collapse of the Han dynasty. Kingdoms have arisen in southern Cambodia, and there Hinduism and Buddhism coexist peacefully. The importation of camels to the Sahara has increased trading there. The Soninke of Ghana is growing as a commercial power. Indonesians are settling in Madagascar.
500 Incompetent government has led to a failure by the Chinese to defend their northern border. A dynasty of Xiongnu kings, the Tuoba Wei, are dominating the whole of northern China, and culturally they are becoming more Chinese. In the south, meanwhile, a recent string of Chinese families had risen and fallen from power while engaging in rampages of murder as a way of settling disputes over who was to rule.