Below is an article by the Daily Star:

Kathin Chibar Dan, one of the largest annual religious festivals of the Buddhist community in Chittagong Hill Tracts, was celebrated at a temple, Ajita Mahathero Dhyani Bihar, of Bandarban district yesterday.

Thousands of devotees from Bandarban, Rangamati and Khagrachhari arrived at the temple where its chief and most venerable monk Bhadanto Ajita Mahathero, known as Dhyani Shadhok Bhante, read out from the Holy Tripitaka.

The festival’s Convener Proshonno Kanti Tanchyanga also read out special prayers seeking peace and religious harmony.

The temple’s monks were also offered or “Dan” robes or “Chibar” which are made of cotton and weaved by devotees overnight, hence the word “Kathin” or difficult is associated with it.
Bishakha, a nurse of Goutama Buddha, introduced the festival about 2,500 years ago.

It marks the conclusion of a three-month seclusion of monks who meditate inside their monasteries for self-edification and atonement for mankind and is preceded by another festival, Probarona Purnima, characterised by the release of sky lanterns.