Introduction: Koh Ker, one of the provincial cities of the Khmer Empire, was located approximately 85 km northeast of the Angkor monuments. The temples in the Koh Ker monuments were mainly constructed from laterite, sandstone and brick between 921 and 944 AD. The laterites used in the Koh Ker monuments are difficult to classify based on their appearance. However, using a portable X-ray fluorescence analyzer it was possible to distinguish two distinct types of laterite based on Sr content. Results: Laterite blocks used in construction of the Koh Ker monuments either had a low Sr content of less than 300 ppm or a high Sr content of greater than 400 ppm. Significant quantities of quartz were observed in the low Sr content laterites, whereas the high Sr content laterites had relatively low quartz content. Differences in the magnetic susceptibility also were observed for these laterites. Using both Sr contents and magnetic susceptibilities of the laterite blocks, in combination with the assumption that the construction site proceeded in an outward manner, we identified five distinct laterite types associated with different stages of construction.

Sambor Prei Kuk is a predominantly brick monument complex identified as Ishanapura, the capital of the Chenla Dynasty, which reached the height of prosperity in the first half of the 7th century. In the east area of this ancient city, the religious area was formed by three temple complexes which are composed of brick shrines and a multiple number of smaller temples with single or a few shrines scattered in the area. One of the challenging issues is to identify the dates and order in which these structures are constructed. Previous studies based on epigraphy and decorative style have estimated a simple dating of the three temple complexes. In this research, 59 major brick structures which are relatively well preserved in this area were analyzed in terms of the size and chemical composition of their component bricks. This analysis revealed that these brick structures can be classified into several groups corresponding to construction stages. The results revealed that the individual shrines in each temple complexes were built in a more complex process than previously stated, and the construction stages of the individual shrines in the vicinity were also identified as an equally complex process.