did it carry any meaning in ancient times?
It is  most commonly referred to a self-governing body or area since the tetrarchy
Prefecture
"Prefecture" most commonly refers to a self-governing body or area since the tetrarchy when Emperor Diocletian divided the Roman Empire into four districts (each divided into dioceses), grouped under "a Vicarius" (a number of Roman provinces, listed under that article), although he maintained two pretorian prefectures as an administrative level above the also surviving dioceses (a few of which were split).
what is the type of government in japan It is the central government of Japan is the country ruled by the emperor or the prime minister? The Prime Minister what is the role of the emperor there then? His role is ceremonial and he has no powers related to Government. what is service period of the prime minister there? four years what divisions of ministries can we find there? UNANSWERABLE how is the law enforcement in the country? It is provided mainly by the prefectural police departments, under the oversight of the National Police Agency and supervised by the Criminal Affairs Bureau of the National Police Agency. what is the uniform of the police department mentioned? The jacket became the turned-down collar style with three buttons, and the vent was done away with. and which weapon do they use? S&W M37 and M360 revolvers, FN Model 1910 or Colt Model 1903 were used for open-carry uses, and Colt Model 1908 Vest Pocket or FN M1905 for concealed carry. what else do they manage? They are responsible for the regular police affairs as to the areas of the respective prefectures what does the term prefecture refer to? It  is an administrative jurisdiction or subdivision in any of various countries
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Prefecture [SEP] Antiquity
"Prefecture" most commonly refers to a self-governing body or area since the tetrarchy when Emperor Diocletian divided the Roman Empire into four districts (each divided into dioceses), grouped under "a Vicarius" (a number of Roman provinces, listed under that article), although he maintained two pretorian prefectures as an administrative level above the also surviving dioceses (a few of which were split).