The Páli name for Siam. There was very close relationship between Ceylon and Siam from the middle ages. For details see J.R.A.S. (Ceylon) xxxii.190ff.
When Buddhism fell on evil days in Ceylon, the kings of that Island turned to Siam for help in the restoration of the Faith. Kittisirirájásíha obtained copies of the Mahávamsa from Siam and completed the chronicle down to his day (Cv.xcix.78f). With the help of the Olandá (Dutch), he sent an embassy to Ayojjhá - capital of Dhammika, king of Siam - asking that a chapter of monks might be sent to Ceylon. Ten monks were sent, with Upáli and Ariyamuni at their head, together with many books and other gifts. The monks took up their residence in the Puppháráma in Sirivaddhanapura (Kandy), and, under the king's patronage, the ceremony of ordination was held on the 2296th year after the Buddha's death, on the full moon day of Ashálha.
Some time later, Dhammika again sent a chapter led by Visuddhácariya and Varañánamuni. As a token of his gratitude, Kittisirirájasíha sent to Dhammika a model of the Buddha's Tooth Relic in Kandy, together with various other gifts. Dhammika returned his courtesy by sending various books not to be found in Ceylon, a replica of the Buddha's footprint found on the Saccabaddha Mountain, etc. Cv.c.63ff., 136 ff.