After the third Buddhist Council Ashoka sent Buddhist mission to several parts of India and to Sri Lanka where he sent Mahendra his son, or in some sources his brother, and daughter Sanghamitra for the spread of Buddhism. The conversion of Sri Lanka into Buddhism is unanimously ascribed to Mahendra.
When Ashoka embraced conversion to Buddhism the other members of his family also followed suit. According to the Buddhist sources, Ashoka’s brother Tissa, his son, daughter and queen Karuvaki also became converts to Buddhism. The famous Queen’s (Minor/pillar) edict in Allahabad refres to the sacred donations made to the Buddhist Sangha (the Buddhist order) by his second queen Karuvaki.
Ashok’a relation with the Buddhist Sangha was that of a royal patron and in this context he tried to rigidly enforce the unity of the Buddhist Sangha. In his minor Rock Edicts he repeatedly warns that “whosoever, monk or nun, breaks up the Sangha, after being clothed in white garments shall be expelled out of the Sangha.” After his conversion to Buddhism, he went on pilgrimages to various Buddhist scared places and built several stupas and viharas.