9 events the sources record for this year, grouped by region.
What happened
West Asia (3)
Darius sets out from Susa to prepare a campaign against the Scythians and has a bridge built across the Bosporus (Herodotus, Histories 4.83-85)tradition
Darius crosses into Europe on the pontoon bridge over the Bosporus (built by the architect Mandrocles) (Herodotus, Histories 4.85-88)tradition
Darius crosses Thrace and sails from Sestos to Asia, leaving Megabazus as governor of Europe (Herodotus, Histories 4.143)tradition
Egypt & North Africa (1)
The Persian army besieges Barca for nine months, breaks its treaty, takes the city, and enslaves its inhabitants (Herodotus, Histories 4.200-203)tradition
Southern Europe (4)
Darius subjects the Getae of Thrace; they resist at first but soon are enslaved (Herodotus, Histories 4.93)tradition
Darius reaches the Ister (Danube), has the Ionians guard the bridge, and crosses his army (Herodotus, Histories 4.97-98)tradition
The Scythians demand that the Ionians dismantle the bridge, but following Histiaeus' advice they guard it and repair it, so Darius' army crosses (Herodotus, Histories 4.133-141)tradition
Hipparchus is killed by Aristogeiton and Harmodius (Herodotus, Histories 5.55-56)
Eastern Europe & Russia (1)
The Scythians avoid a pitched battle and retreat, drawing the Persian army on; they burn the city of the Budini (Herodotus, Histories 4.120-127)tradition