The Ethnogenesis of the Croats studies the occurrence , the origin and development of the Croatian people. Different interpretations of the origin of the Croats, and the time of their settlement in the Roman province of Dalmatia, occur very early. Ethnicity can be understood as the continuity of the community, regardless of changes in members of the community, language and cultural features. In the 10th century Byzantine Emperor Constantine VII historian. Porphyrogenitus recorded the arrival of the Croats, during the reign of Emperor Heraclius. This is probably the first direct mention of the Croatian name in the domestic sources, when the prince Trpimir named himself "Duke of Croats". This Latin form of the Croatian ethnonym was confirmed on stone inscriptions: Branimir inscription from Sopot near Benkovac, and in Drzislav from Kapitul near Knin. The management of the empire is the work of the Byzantine emperor Constantine VII. Porfirogenet from the 10th century written in the Greek language. This is the most important file for the Croats and the history of the South Slavs. The work provides very important information about the earliest history of the Croats; records the folk tradition of the homeland and the incursion of the Croats, the collapse of Byzantine rule in Dalmatia, the Croats fighting with neighboring nations, and gives information about Croatian counties and cities. The work is one of the most important and the key sources of the early medieval Croatian history. Ancient Croats arrived in Europe from Iran in the late 18th century. They were discovered, also, old records that point to the possibility that Croats used to be an Iranian tribe.