That depends on how you count the years. If you are using the Gregorian Calendar, which is the one that we use here in the West, then all you need to do is subtract 2,020 from 90,036 and add a B.C. at the end (B.C. = Before Christ - yes, this is still used and accepted within academic circles, despite what progressive public school teachers think). There are multiple types of calendars to track time, mostly divided into a solar calendar, a lunar calendar or a lunisolar calendar. Therefore, it depends on the type of calendar that you are using to calculate the accurate year.