Chaldean Language

Concise Bible Dictionary:

At Babylon Daniel and his companions had to acquire “the learning and the tongue of the Chaldeans,” that is, their ancient literature and language (Dan. 1:4). The question is what was that language? In Daniel 2:4 we find that the wise men answered the king in the Syriac language, that is Aramaic: (Compare Ezra 4:7). The Hebrew language is held to be closely related to the Aramaic: that the two are not the same is evident from Isaiah 36:11, where the Jewish leaders asked Rabshakeh to speak in the Syrian language, and not in the Jews’ language, that the Jews generally should not understand what was said. There must be some reason why in Daniel it is said the wise men answered the king in “Aramaic”; this is held to be not the learned and court language, but the common language of the people; and the wise men may have used it that all who heard it might judge of the reasonableness of what they said, though the king might condemn them. The language spoken at court would be different and has been judged by some to be a branch of the Aryan dialect, the ancient language of Central Asia; or perhaps it may have been the ancient Accadian.
As to the writing, the inscriptions found at Assyria, Babylon, and Persia are cut in stone or stamped on bricks in the cuneiform (that is, wedge-shaped) characters. It is known that there was an earlier mode of writing by hieroglyphics which could easily be painted upon papyrus, but which could not without great labor be cut in hard stone, and it is probable that this led to the adoption of the wedge-shaped characters, in which there are no curves: by the variation in position, and number of short and long wedges every sound could be represented, and every proper name spelled. Darius is thus represented on a Persian inscription at Behistun.
Darius