The Dry Tree (or Solitary tree) is a legendary tree. The first recording about it was done by Marco Polo, somewhere in the wastelands of northern Persia. According to Polo, it was the only tree within hundreds of kilometres of desert. The legend said that the Dry Tree marked the exact spot of the great battle between Alexander the Great and Darius. It is not clear whether this 'great battle' refers to the battle of Issus or of Gaugamela, or both. The purported location—somewhere in Khorasan, near the border with present day Turkmenistan—is also impossible to ascertain, because Darius had already been assassinated when Alexander reached these regions.