Festivals in the Kingdom of Bhutan are rich and happy expressions of its ancient Buddhist culture. These religious festivals are locally known as Tsechu which means tenth day of a month in Bhutanese lunar calendar corresponding to the birthday of Guru Rinphoche. Tsechus are held throughout Bhutan in honour of Guru Rinpoche, the saint who introduced Buddhism to Bhutan in the 8th Century. Festivals are held from 10th day of auspicious Bhutanese months at the dzongs (fortresses) or at monasteries and usually last for 3 to 5 days. During Tsechus religious mask dances and folk dances are performed with occasional entertainment by Astara (clowns).