We've gone through slave and feudal societies, and the unenlightened social systems have just left us for less than one hundred years. The good and bad cultural customs accumulated in thousands of years have been putting its imperceptible influence on us in every aspect of our social lives, including the pattern of our thinking and behavior
"have just left us for less than one hundred years"
i would work on that part
'have been gone for less than one hundred years', 'are not even one hundred years in the past' 'less than a century ago' 'within the last century' 'were still practiced within the last one hundred years', something
"The good and bad cultural customs ... have been putting its ...."