Phrip Phri (Thai: พริบพรี) or Srijayavajrapuri, later known as Phetchaburi, was a Xiān political entity located on the west coast of the Bay of Bangkok, lower central Thailand. It was established in the 12th century by a royal Pprappanom Tteleiseri from Soucouttae/Locontàï. Previously, the city was a maritime-oriented port on the ancient trade route between India and China during the Dvaravati period, but was abandoned around the 11th century following the decline of the Dvaravati civilization.

In the 12th century, Phrip Phri was possibly under Lavo's Ayodhya since several royals from Ayodhya were appointed the rulers of Phrip Phri, as mentioned in local chronicles and legends. It then became the vassal of the emerging Siamese Sukhothai and later formed part of the Ayutthaya kingdom in 1351, which made it functioned as a significant fortified frontier of Ayutthaya.

Human settlement in Phetchaburi dates back to the prehistoric era, according to archaeological evidence found in caves and rock shelters, such as Ban Nong Fab in the west of Tha Yang district, and Tham Fa Tho in Mueang district. Several settlements dating to the Metal Age in the late prehistoric period have been discovered on the plains and coastal area. Prominent archaeological sites from the Iron Age include Ban Khok Phrik, an ancient community established on a large hummock along the coastline in Khung Krathin sub-district, Mueang district, Ratchaburi. This community performed burial rituals, established relationships with other communities at important regional mineral sites, and had maritime connections with faraway communities for bartering foreign goods.

Although no traces of Dvaravati-style communities have been found in the Phetchaburi River basin, many historic sites and artifacts dating to the Dvaravati Period (6th-11th centuries), including Buddha statues and sculptures of the Wheel of Dhamma, were found scattered in the area. In Ban Lat district, traces of buildings and stone statues were recovered at Ban Nong Phra and pieces of earthenware, moulds of Buddha statues and glass beads in Noen Pho Yai. Traces of human settlement and historic sites were found near Khao Krajiew of Tha Yang district, while ruins of a large religious building were uncovered in Thung Setthi, Cha-am district. Trade ties with other communities in faraway lands from the late Metal Age onwards contributed to the formation of large communities on fertile alluvial plains. These components made the location suitable for cultivation and settlement, as evidenced by archaeological sites and religious monuments from the Dvaravati period.

There is no clear evidence to confirm the year of the establishment of Phrip Phri. However, the base of Wat Maha That [th] main stupa is made of large bricks in the Dvaravati art style, the pagoda is in the Ayutthaya style [th], and several temples that has a large red sandstone Buddha statue in the pre-Ayutthaya U Thong Style, given such evidence, Phrip Phri must have been founded before the Ayutthaya period - possibly when Buddhism spread from Ceylon via the southern city of Nakhon Si Thammarat.

According to the Instructions Given to the Siamese Envoys Sent to Portugal composed in 1684, Phrip Phri was built in 1157/58 by King Sommedethia Pprappanom Tteleiseri Maahesa Vorauaarintti Raacha Boppitra (สมเด็จพระพนมทะเลศรีมเหสวัสดิราชาบพิตร) from Soucouttae (Sukhothai). The kingdom had four kings who reigned for 163 years. The last king, Sommedethia Praa Raamaattibodi Bopptra (สมเด็จพระรามาธิบดีบพิตร, or Uthong V), then founded the Ayutthaya Kingdom in 1351. This conforms with the Nakhon Si Thammarat Chronicle [th]. In contrast, Du Royaume de Siam of Simon de la Loubère cites Pra Poa Noome Thele Seri (พระพนมไชยศิริ), the King of Locontàï (Nakhon Thai), who ascended to the throne in 1188, was the founder of Phrip Phri. The period during which Pra Poa Noome Thele Seri moved from Yassouttora Nacoora Louang or Tasoo Nacora Louang to Locontàï, around the 1150s, was the time when Angkor began to re-expand its influence to Lavo. Some believed the house of Pprappanom Tteleiseri which ruled Lavo's Ayodhya and Phrip Phri was the Mon, and the rivalry, house of Suphannabhum, was the Tai, but A. B. Griswold proposed that the house of Suphannabhum was perhaps more Mon or Khmer, and another was definitely Tai.

To the north, the Legend of Singhanavati mentions the movement of Chaiyasiri, a Tai royal of the Singhanavati clan, to found Nakhon Thai in the 6th century, and several Thai scholars propose that Pprappanom Tteleiseri was the descendant of the legendary Phrom, who was the father of Chaiyasiri. Because of that, the house of Singhanavati at Nakhon Thai might have established royal intermarriage with the Mon dynasty in the area since another lineage of Pprappanom Tteleiseri was said to be from Yassouttora Nacoora Louang, which equated to Yaśodharapura of Angkor, or ฺTasoo Nacora Louang (ธาตุนครหลวง), as cited in the Du Royaume de Siam. However, the exact time mentioned in the Legend of Singhanavati remains controversial.

The following shows the movement of Siamese dynasties before the traditional foundation of the Ayutthaya Kingdom, based on the texts provided in the 1684 Instructions Given to the Siamese Envoys Sent to Portugal, Voyage de Siam of Guy Tachard, and the Du Royaume de Siam of Simon de la Loubère.