Ancient India represented a distinct tradition of law, and had an historically independent school of legal theory and practice. The "Arthashastra", dating from 400 BCE and the "Manusmriti", from 100 CE, were influential treatises in India, texts that were considered authoritative legal guidance. Manu's central philosophy was tolerance and pluralism, and was cited across Southeast Asia. Early in this period, which finally culminated in the creation of the Gupta Empire, relations with ancient Greece and Rome were not infrequent. The appearance of similar fundamental institutions of international law in various parts of the world show that they are inherent in international society, irrespective of culture and tradition. Inter-State relations in the pre-Islamic period resulted in clear-cut rules of warfare of a high humanitarian standard, in rules of neutrality, of treaty law, of customary law embodied in religious charters, in exchange of embassies of a temporary or semi-permanent character.