Boh, a Celtic people whose original seat appears to have been in that region now forming the French departments of Haute-Marne and Haute-Saone, but who passed over into Cisalpine Gaul, by the Great St. Bernard or the pass of the Pennine Alps, probably with the current of Celtic immigration which began to set thither as early as the 5th century B. C. (See Celts.) They crossed the Po, and established themselves south of that river, in the region forming the modern provinces of Modena, Bologna, and Ferrara. In the half-traditionary accounts of the period subsequent to this settlement, they are represented as aiding the fasubrefl and Senones in the sack of Melpum (probably about 396 B. C.). Their first conflict with the Romans appears to have been in 288, when they acted as allies of the Etruscans at their defeat near Lake Vadimonis. In 282 they were again defeated, and now kept a truce with Rome for 45 years. At the end of that time they again took up arms to resist Roman encroachments, played a prominent part in the Gallic war of 225, in which they Buffered severe defeat, in the second Punic war (218), in which they were efficient allies of Hannibal, and in the revolt of the Gauls under Hamilcar (200). They did not cease hostilities, waged with or without the assistance of other tribes, until 191, when they were finally entirely subdued by Scipio Nasica, who punished them with the utmost severity, slaughtering nearly half their number.

As a further means of putting an end to their power, the Romans established colonies in their territory, and finally compelled the remaining Boii to re-cross the Alps, and take refuge with the Celtic tribes of Pannonia. Near the W. border of this country they again established themselves, in the regions which took from them the names of Boioaria or Bavaria and Boiohemum or Bohemia. They remained here for more than a century, but their power had been broken, and they were at last entirely exterminated by the Dacian tribes. Little is known of their customs and political condition, but from the allusions of Livy they appear to have had towns and fortifications of some consequence, and to have known something of the mechanic arts.