Tegana was a 13th century Mongol war lord. He posed as a peace emissary from Noghai to Kublai Khan in 1289 and travelled with Marco Polo’s caravan.
When the First Doctor and his companions joined the group, Tegana was suspicious of them. He wanted to destroy them as evil spirits, but Polo stopped him.
During their travels, Tegana tried to make Polo suspicious of the Doctor’s group. At the same time, however, Tegana was making arrangements for a group of bandits to attack Polo‘s camp. Each time, he was defeated, but Polo never suspected him and refused to believe Ping-Cho and Susan when they accused him of helping to kidnap Barbara.
Tegana also tried to steal the TARDIS for Noghai, but it was eventually brought to Peking.
In Peking, Tegana attempted to assassinate the Khan, but Polo stopped them and they fought. Polo defeated him, and he subsequently committed suicide.