It existed everywhere. All civilizations had caste systems until Christianity destroyed it under the belief that all are equal in God's eyes
The pollution in India has more to do with their culture, which places extreme concern towards their appearances and reputation than actual merit. Higher castes don't want to clean because it makes them look bad. Lower castes don't want to clean because they either want to be perceived as higher or out of spite
Japan had caste systems too, except that it revolved around seniority. It is super strict that they still have a fax machine because the boomers are in charge and they refuse to innovate, which is the second largest factor to their economic stagnation. Their biggest corps are all over 40 years old. Nothing new ever came up because they refuse to entertain new blood
Also, this seniority system is ridiculous to the point that even if it was just a day of difference, it means that the older one is in charge and you are not allowed to question it. Those who stand out get hammered down
Similar things happened in Rome, Greece, and other countries until Christianity came along