The year of the Jews, even from their coming out of Egypt, was Luni- solar. It was solar, for the harvest always followed the Passover, and the fruits of the land were always gathered before the feast of Tabernacles, Leviticus 23. But the months were lunar, for the people were commanded by Moses in the beginning of every month to blow with trumpets, and offer burnt offerings with their drink offerings, Numbers 10:10, Numbers 28:11, 14; and this solemnity was kept on the new moons, Psalm 81:3, 4, 5. 1 Chronicles 23:31. These months were called by Moses the first, second, third, fourth month, &c. and the first month was also called Abib, the second Zif, the seventh Ethanim, the eighth Bull, Exodus 13:4. 1 Kings 6:37, 38; 1 Kings 8:2. But in the Babylonian captivity the Jews used the names of the Chaldean months, and by those names understood the months of their own year; so that the Jewish months then lost their old names, and are now called by those of the Chaldeans.
The Jews began their civil year from the autumnal Equinox, and their sacred year from the vernal: and the first day of the first month was on the visible new moon, which was nearest the Equinox.
Whether Daniel used the Chaldaic or Jewish year, is not very material; the difference being but six hours in a year, and 4 months in 480 years.
But I take his months to be Jewish: first, because Daniel was a Jew, and the Jews even by the names of the Chaldean months understood the months of their own year: secondly, because this Prophecy is grounded on Jeremiah’s concerning the 70 years captivity, and therefore must be understood of the same sort of years with the seventy; and those are Jewish, since that Prophecy was given in Judea before the captivity: and lastly, because Daniel reckons by weeks of years, which is a way of reckoning peculiar to the Jewish years. For as their days ran by sevens, and the last day of every seven was a sabbath; so their years ran by sevens, and the last year of every seven was a sabbatical year, and seven such weeks of years made a Jubilee.