Sri Lankan President Maithripala Sirisena's three-day official visit to Thailand aims to cement close religious and trade ties between the two countries, according to the government.
Mr Sirisena made the trip after an invitation by Prime Minister Prayut Chan-o-cha and he will meet the premier at Government House today.
His visit, which started yesterday and ends on Wednesday, marks the 60th anniversary of diplomatic ties between the two countries.
Gen Prayut and the Sri Lankan premier, who took office in January this year, will discuss tourism, culture and education cooperation when they meet today, according to authorities.
Sri Lankan businessmen accompanying Mr Sirisena on his trip will meet their Thai counterparts to discuss trade, while Mr Sirisena and Deputy Prime Minister Somkid Jatusripitak will meet to discuss trade and investment ties tomorrow.
The Sri Lankan premier has also brought relics of Lord Buddha on his visit to allow Buddhists in Thailand to pay homage to them.
Some of the Buddha's relics from Sri Lanka have previously been brought to an expo in Thailand, but a Buddhist expert said the ones accompanying Mr Sirisena were more meaningful as they came from a historic place.
Kanok Sanprasert, deputy director of the National Office of Buddhism, said the relics were from Lord Buddha's cervical spine and were enshrined in the ancient temple Mahiyangana Raja Maha Viharaya, built in the area where Gautama Buddha left his footprints. He said it was the first time these particular religious relics have left the country since they were placed in the temple.
Mahiyangana is believed to be the site of Lord Buddha's first visit to the country, around nine months after his enlightenment. It is believed that Buddha came there to mediate a conflict between local tribes. The tribes solved the dispute with his help and then asked for a token from him before he returned to India so they could worship in his absence.
Buddha gave them a handful of hair from his head, which were enshrined inside a small stupa. Following his death and cremation in Kusinara, a worshipper recovered his cervical spine, or neck bone and brought it to the temple. This was enshrined within the same stupa, which was enlarged.
The Sri Lankan ambassador to Thailand, Kshenuka Senewiratne, said the cordial relationship between the countries stemmed from shared religious beliefs which began when Theravada Buddhism from Sri Lanka was introduced to the kingdom in the 13th century.
"Although we have enjoyed a diplomatic relationship for 60 years, our religious ties have been strong since Lanka Vamsa Buddhism entered Thailand 800 years ago," Ms Kshenuka said, adding that Thais and Sri Lankans regularly visit religious sites in each other's homelands.
The Buddha relics will be kept at Buddha Monthon monastery in Nakhon Pathom, and open for the public to pay homage until Nov 16.
Pirith chanting will be conducted today by 60 Sri Lankan Bhikkhus and senior Thai monks at Phutthamonthon.
Mr Sirisena will also present a Buddha statue as a gift to Wat Dhammaram in Ayutthaya, which was the temple residence of famous monk Phra Upali Maha Thera before he travelled to Sri Lanka in 1755.
On the political front, in 2002 Thailand hosted the Sri Lankan government and the Tamil separatist group Liberation Tigers of Tamil Eelam for peace talks.