[akiselev]

This really depends on your state and on how textbooks are chosen. My middle school (California pre-CORE) petitioned the State Board of Education and was allowed to use a previously unapproved world history textbook that gave equal coverage to the Persian Empire up to the point we stopped in class. World history in my high school also devoted many chapters to it as did US history, although much less for the latter. (We covered each chapter linearly until we ran out of time in the school year but I dont know if thats what most schools do)

For better or worse, state and local governments have a lot of influence on the textbooks and curriculum. Unfortunately cost seems to be the main driving factor for most textbook selections which means that only the bare minimum beyond western historical canon is covered.