Plato  Were there any known thinkers/writers particularly beyond
Greece in the east that influenced Plato? And what were their
writings? It is difficult to imagine that he appeared de novo without
standing on the shoulders of predecessors.
This is similar to a question submitted several years ago, but this
time art is not my primary consideration.
Thank you
William Reilly

Plato himself acknowledged the debt he owed to his predecessors. Most
of his dialogues feature his mentor, Socrates, in the central role.
Plato's debt to Parmenides and Zeno of Elea is noted in his dialogue,
'Parmenides'.

 And Heraclitus's ideas are debated in the 'Theaetetus' (150 onwards).
In the 'Timaeus' and the 'Critias' Plato discusses the Atlantis legend
which he claims to have got from Solon, who got it from the Egyptians.

If you read Plato's works and take a look at the Pre-Socratic thinkers
then you can find many elements which were either directly drawn from
earlier thinkers or were stimulated by disagreements with them.