Hosea son of Beeri prophesied about the middle of the eighth century b.c., his ministry beginning during or shortly after that of Amos. Amos threatened God’s judgment on Israel at the hands of an unnamed enemy; Hosea identifies that enemy as Assyria (7:11; 8:9; 10:6; 11:11). Judging from the kings mentioned in 1:1, Hosea must have prophesied for at least 38 years, though almost nothing is known about him from sources outside his book. He was the only one of the writing prophets to come from the northern kingdom (Israel), and his prophecy is primarily directed to that kingdom. But since his prophetic activity is dated by reference to kings of Judah, the book was probably written in Judah after the fall of the northern capital, Samaria (722–721 b.c.)—an idea suggested by references to Judah throughout the book (1:7,11; 4:15; 5:5,10,12–13; 6:4,11; 10:11; 11:12; 12:2). Whether Hosea himself authored the book that preserves his prophecies is not known. The book of Hosea stands first in the division of the Bible called the Book of the Twelve (in the Apocrypha cf. Ecclesiasticus 49:10; see essay, p. 1790) or the Minor Prophets (a name referring to the brevity of these books as compared to Isaiah, Jeremiah and Ezekiel).
http://www.biblica.com/en-us/bible/online-bible/scholar-notes/niv-study-bible/intro-to-hosea/
http://www.biblica.com/en-us/bible/online-bible/scholar-notes/niv-study-bible/intro-to-hosea/