The tradition of holding the Great Prayer Festival was started by master Tsongkhapa. He chose the first 15 days of the new year to commemorate an event in the life of Shakyamuni Buddha. The Sutra of the Wise and Foolish recounts how the Buddha finally responded to a challenge from six non-Buddhist teachers by displaying miracles for 15 days before a crowd of several hundred million, inspiring profound spiritual realisations in all those present.
Before the first Great Prayer Festival in Lhasa, master Tsongkhapa had just completed the renovation of the Jokhang, the most sacred temple in Tibet. His fervent aspiration was for the flourishing of the Buddha's teachings and the happiness of all sentient beings. With this motivation, he offered a crown of pure gold studded with jewels to the most precious Jowo Buddha statue, and silver crowns to other statues. Each day during the festival, gold powder was offered to the faces of the statues, and on the 8th and 15th days, gold was applied to the whole statue. Monastic robes and brocade clothes were offered to all the statues, and the entire temple was adorned with countless silk brocade banners, pennants, parasols, and other ornaments.
So many thousands of butter lamps were lit that the stars could not be seen in Lhasa's night sky. Clouds of incense smoke permeated the city day and night. Hundreds of bowls with water perfumed by Indian saffron, and 108 large ornate butter sculptures decorated altars. These offerings were distributed to the poor afterwards. Sponsors made generous offerings to the thousands monastics who had gathered, and master Tsongkhapa taught one session on the Jataka tales (Buddha's past life stories) each day. Through these merits, hundreds of thousands of people were set on the path to a higher rebirth, liberation, and enlightenment.
Over time, the tradition developed and spread to monasteries throughout Tibet, Mongolia, and now around the world. It incorporated other elements such as the final debate examinations for the highest scholastic degree (Geshe Lharampa) in the Gelug education system. However, the purpose of the festival has remained the same: to ensure the flourishing of the Buddha's doctrine, and the happiness of all sentient beings.