Image depicting the journey of the tooth relic. The sacred tooth
relic was brought to Sri Lanka in the 4th century CE safely stored
in the hair of a princess.
The bridge to this cult of the Buddha is the relic.
Relics may be of the Buddha or of any arhat (enlightened person), male or female. However, in practice only relics of the Buddha are important. They have been divided by doctrine into three classes: 1) pieces of the body, 2) things he used and 3) reminders or representations. The worship of relics resolves the clash of the cognitive fact of the Buddha's absence with the psychological fact of his presence.
We already hear of relics in the Canon. Shortly after the Buddha's last words, in the same text, is recounted how after the Buddha's body had been cremated all the peoples of that area sent asking for his remains. They were divided into eight parts by Dona; a tribe who applied late got the embers of the pyre, and Dona kept the vessel in which the remains had been collected. The original text ends by telling us that there were then ten portions, and for each a stupa (shrine) was built and a festival celebrated.
To this is appended a verse, which Buddhaghosa says was added in Ceylon (Sri Lanka), which adds to the earlier eight portions of bodily remains four teeth, one of which was allegedly in heaven, and another in Kalinga in South India. This latter became of great importance to the Sinhalese, for it was brought to Ceylon in the fourth century, and from that time on accompanied the king of Ceylon, and had a temple in its honour in his capital.