Prince Naret was born in the city of Phitsanulok on 25 April 1555. He was the son of King Mahathammarachathirat of Phitsanulok and his queen consort, Wisutkasat. His mother was a daughter of Maha Chakkraphat and queen consort Suriyothai. His father was a Sukhothai noble who had defeated Worawongsathirat in 1548 and put Maha Chakkraphat on the throne. Prince Naret, also known as the "Black Prince" (Thai: พระองค์ดำ), had a younger brother Ekathotsarot, known as the "White Prince", and an elder sister, Suphankanlaya.[2]:67
In the second siege of Ayutthaya (1563–64), King Bayinnaung of the Taungoo Dynasty of Bago, Burma (formerly known in Burmese as Hanthawaddy (Burmese: ဟံသာဝတီ and in Thai as rtgs: Hongsawadi หงสาวดี) led massive armies, invading the country and laying siege to Phitsanulok. Maha Thammarachathirat came to believe that the city would not be able to withstand a long siege due to a scarcity of food and a smallpox outbreak, so he surrendered the city. King Bayinnaung took Phitsanulok and made the Sukhothai Kingdom a Burmese tributary state; and required Maha Thammarachathirat to send his son—the Black Prince—to Bago as a hostage to ensure the king's fidelity.[2]:36,67