Cross reference
Mark 5:20
20 and he went away, and began to proclaim in the Decapolis how great things Jesus did to him, and all were wondering.
Matthew 4:25
25 And there followed him many multitudes from Galilee, and Decapolis, and Jerusalem, and Judea, and beyond the Jordan.
Mark 7:31
31 And again, having gone forth from the coasts of Tyre and Sidon, he came unto the sea of Galilee, through the midst of the coasts of Decapolis,