* Phra Kru are the amulets which were created by ancestors and kept in the hiding places for inheritance of Buddhism. The different arts of Buddha images in amulets are according to the respective historical periods by;
Dvaravati Period (7-11th A.D.)
Khmer and Lopburi Period (11-13th A.D.)
Chieng Saen-Haripoonchai-Lanna Period (11-18th A.D.)
Sukhothai Period (12-15th A.D.)
U-Thong (12-15th A.D.)
Ayutthaya Period (13-18th A.D.)
Rattankosin Period (19th A.D. till now)
* The repository sites of Phra Kru in Thailand were discovered in various regions of Thailand. The most popular Phra Kru is "Phra Kru Lanna" where located in Lampoon province, Northern of Thailand. Phra Rod, one of Benjapakee set, was found in this Kru including Phra Bang, Phra Kong and Phra Perm which are well known among Phra Kru collectors as well. Besides Phra Kru of Lampoon family, other famous Phra Kru are classified by the following regions;
- Northern Region: Kru Kampangpetch, Sukhothai / Srisatchanalai, Pitsanulok, Kru Chieng Saen, Kru Hod Chieng Mai, Kru Srithep Petchaboon, etc.
- Central Region: Kru Ayutthaya in various ancient temples, Kru Suphanburi, Kru Lopburi, Kru Thakradan Kanchanaburi, etc.
- North Eastern Region: Kru Nadoon Mahasarakham
- Southern Region: Kru Surathani, Kru Nakornsrithammaratch, etc.