Which earlier geographer’s writings and maps did Ptolemy use for his geographic work?

Ptolemy primarily based his geographical work, the Guide to Geography, on the maps and writings of the geographer Marinus of Tyre (c. 100 ce).1

By his own admission, Ptolemy did not attempt to collect and sift all available geographical data himself. Instead, he relied on Marinus’s cartographical work, only selectively introducing more current information, particularly regarding the Asian and African coasts of the Indian Ocean. Much of what is known about Marinus today exists only because Ptolemy preserved the substance of his work. Additionally, while Ptolemy utilized older maps and travelers' accounts to determine the locations of roughly 8,000 places, his work was part of a long tradition of Greek geographic development that included figures such as Eratosthenes, who also contributed to the evolution of the reference-line systems Ptolemy later refined.12