After the Khmer Empire collapsed, the Thai building masters of the Sukhothai Kingdom adapted the Prang form. They extended and developed it. The building material was no more separate small sandstone blocks, instead the Thais built the Prang in brick or laterite covered with stucco. And the cella could be reached only by stairs. An example for this is the Prang of the Wat Mahathat in Phitsanulok. Later developments of the Prang suggested the cella only. The entrance door became a niche, in which was placed the "Buddharupa" (Buddha statue), which had originally taken the central position inside. For reasons of symmetry the niche was repeated on all four sides. On its pinnacle was a Trishul, the "weapon of Indra".