A number of historic Jewish events occurred on the 15th of Av:
The Sanhedrin issued a ruling (circa 1200 BCE) allowing women who had inherited land to marry outside their tribe and retain their inheritance. Previously, the daughters of Tzelafchad had won the right to inherit land only on condition that they marry within their tribe, so that ancestral lands remain within their original tribal territory.
The same Sanhedrin allowed men of other tribes to marry women from the tribe of Binyamin. The tribes had censured the tribe of Binyamin for the incident of The Concubine at Givah, and swore not to marry with them, but now the ban was lifted.
