Aspadana

Aspadana contains certainly as its first element the root acpa, "horse."

The Seven Great Monarchies Of The Ancient Eastern World, Vol 3. (of 7): Media The History, Geography, And Antiquities Of Chaldaea, Assyria, Babylon, Media, Persia, Parthia, And Sassanian or New Persian Empire; With Maps and Illustrations. George Rawlinson 1857

The suffix dan may perhaps be a corruption of ctana, analogous to that which has produced Hama-dan from Hagma-ctan; or it may be a contracted form of danhu, or dairihu, "a-province," Aspadana having been originally the name of a district where horses were bred, and having thence become the name of its chief town.

The Seven Great Monarchies Of The Ancient Eastern World, Vol 3. (of 7): Media The History, Geography, And Antiquities Of Chaldaea, Assyria, Babylon, Media, Persia, Parthia, And Sassanian or New Persian Empire; With Maps and Illustrations. George Rawlinson 1857