Located in the eastern delta of Egypt.
(The ESV Study BibleTM, English Standard Version (ESV) by Crossway Bibles. Page 1448)
Jeremiah prophesied that the men of Memphis and Tahpanhes have shaved the crown of Israel's head, and they brought it upon themselves by forsaking the LORD their God. (Jeremiah 2:16)
The remnant of Judah was taken to Egypt by the commanders of the forces, arriving at Tahpanhes. The LORD told Jeremiah to hide large stones in the mortar in the pavement where Nebuchadnezzar's throne would be set before directing him to tell Judah of His mission to send the king the cleanse Egypt.
The word of the LORD reflecting on the destruction of Judah came to Jeremiah at Migdol and was preached to the remnant, scattered through Migdol, Tahpanhes, Memphis, and Pathros. Also, the word about the coming of Nebuchadnezzar king of Babylon to strike Egypt.
(Jeremiah 44, 46)