The earliest reference to Rain is in a document of the monastery at Niederschönenfeld dated 4 July 1257, wherein it is described as a civitas nostra or ducal town.

Tilly withdrew his troops to Ingolstadt, where he died from tetanus from an infected gunshot wound in his thigh.

Rain's architectural heritage also includes the Roman Catholic parish church of St John the Baptist, which features late Gothic frescoes dating from about 1480.

The four Lachner brothers, Theodor, Franz, Ignaz and Vinzenz, were nineteenth-century German composers, all of whom were born in the town.

Other historic figures from Rain include lawyer and astronomer Johann Bayer (1562–1625), humanist Georg Tannstetter (1482–1535) and pianist Michael Raucheisen (1889–1984).