During the later part of the Malla era, Kathmandu Valley comprised four fortified cities: Kantipur, Lalitpur, Bhaktapur, and Kirtipur. These served as the capitals of the Malla confederation of Nepal. These states competed with each other in the arts, architecture, aesthetics, and trade, resulting in tremendous development. The kings of this period directly influenced or involved themselves in the construction of public buildings, squares, and temples, as well as the development of water spouts, the institutionalization of trusts (called guthis), the codification of laws, the writing of dramas, and the performance of plays in city squares. Evidence of an influx of ideas from India, Tibet, China, Persia, and Europe among other places can be found in a stone inscription from the time of king Pratap Malla. Books have been found from this era that describe their tantric tradition (e.g. Tantrakhyan), medicine (e.g. Haramekhala), religion (e.g. Mooldevshashidev), law, morals, and history. Amarkosh, a Sanskrit-Nepal Bhasa dictionary from 1381 AD, was also found. Architecturally notable buildings from this era include Kathmandu Durbar Square, Patan Durbar Square, Bhaktapur Durbar Square, the former durbar of Kirtipur, Nyatapola, Kumbheshwar, the Krishna temple, and others.