How long were the Hebrews in bondage?

According to Exodus 12:40-1, the Egyptian Captivity was for a period of 430 years.

However, scholars long ago noted that there is a contradiction between this period and the genealogy of Moses. A Jewish midrash (non-binding theological opinion) of the Common Era attempted to rationalise by stating that Moses protested to God that he could not lead the Hebrews, because they had only been in Egypt for 210 years and had not yet faced the 400 years of oppression that God had foretold to Abraham. God responded that the time of oppression had to be dated from the birth of Isaac, and so 400 years had indeed gone by. This midrash implies that the Egyptian Captivity was only for 210 years.

Scholars say that the Israelites were not really enslaved in Egypt - this was a legend that developed long after they had forgotten their real heritage.