What is associated with: around 4000 bc communities of people settled in the yellow river valley in what is today this country?

What is associated with: around 3600 bc king menes of egypt set this precious metals value at two fifths that of gold? Based on the clue 'around 375 bc in the republic he opined that astro...', what is the answer? Based on the clue 'around 387 bc this student of socrates founded the...', what is the answer? Based on the clue 'around 400 bc the greek ctesias described it as ha...', what is the answer? Based on the clue 'around 405 ad this future patron saint was capture...', what is the answer? Based on the clue 'around 418 bc euripides wrote a play named for thi...', what is the answer? Based on the clue 'around 430 this large temple on the acropolis was ...', what is the answer? Based on the clue 'around 447 bc this group led by the scourge of god...', what is the answer?