25 events the sources record for this year, grouped by region.
What happened
China (1)
When King Nan died, the people of Zhou fled east; Qin took the Nine Tripods and other treasures and moved the Lord of Western Zhou to Danhu. (Records of the Grand Historian (Shiji), Annals 史記卷004 周本紀)
South Asia (19)
Ashoka had the Dharma edict inscribed and banned animal sacrifice and festive gatherings (samaja); where the royal kitchen once slaughtered hundreds of thousands of animals daily, only two peacocks and one deer are now killed, and even these will stop (Edicts of Ashoka RE1 Girnar A–H)
Medical care for people and animals was established throughout the king's territory and on its borders (the Cholas, Pandyas, Satiyaputras, Keralaputras, Tamraparni, and the Greek king Antiochus and his neighbors), with medicinal herbs, roots and fruits imported and planted, and trees and wells made along roads (Edicts of Ashoka RE2 Girnar A–D)
Long-standing killing and disrespect toward relatives, Brahmins and shramanas were replaced by the practice of Ashoka's Dharma: the drum-sound became the sound of the Dharma, and divine sights such as celestial chariots, elephants and balls of fire were shown to the people (Edicts of Ashoka RE4 Girnar A–C)
In the 13th year of his reign he first appointed Dharma Ministers (Dharmamahamatras) and sent them to people of all sects, including the Greeks, Kambojas, Gandharas, Rishtikas and Petenikas on the western frontier (Edicts of Ashoka RE5 Girnar H–J)
Dharma Ministers were required to work in the king's capital and in all outlying cities (RE5 M) (Edicts of Ashoka RE5 Kalsi M)
Formerly there was no system for handling affairs and reports, but now reporters may inform the king about the people's affairs at any time — while he eats, in the women's quarters, in the stables, in the palanquin, in the gardens — and the king attends to them everywhere (Edicts of Ashoka RE6 Girnar B–E)
He wishes all sects to dwell together everywhere — for all desire self-control and purity of heart (Edicts of Ashoka RE7 Girnar A–E)
He points out the many ceremonies (mangala) people perform in illness, marriage and the like, and recommends the ceremony of the Dharma instead (Edicts of Ashoka RE9 Girnar A–B)
He declares that he seeks neither fame nor glory but only that the people follow the Dharma, and that danger means demerit (evil karma) (Edicts of Ashoka RE10 Girnar A–D)
He preaches that the "gift of the Dharma" (courtesy toward slaves and servants, respect for parents, non-killing) is the greatest gift (Edicts of Ashoka RE11 Girnar A–E)
In the spring of the third year of King An Dương, a divine man appeared at the city gate and asked when the wall-building would be finished (legend of the construction of Cổ Loa citadel). (Đại Việt sử ký toàn thư 外紀卷之一 「丙午三年（公元前二五五年）春，三」)
Egypt & North Africa (2)
Maka (Magas of Cyrene) is named among the westernmost places reached by the conquest by Dharma (Edicts of Ashoka RE13 Kalsi Q)
The Spartan Xanthippus arrives in Carthage with mercenaries (Polybius, Histories 1.32)
Southern Europe (2)
Xanthippus defeats the Romans with elephants and cavalry; Regulus is beaten (Polybius, Histories 1.34)
The Roman fleet is mostly destroyed in a storm off Camarina (Polybius, Histories 1.37)