How did the Vaiysha, Shudra and the Untouchables help make up the caste system...

In ancient age Vaishya, Sudra and untouchables were the third and lower most class of the caste system. Vaishya dealt with business and trades whereas Sudras dealt with mediocre job of the society.

Explanation:

In the ancient time period Varna or caste system were enlightened by four major class or groups. Among them Brahmins were the first and foremost important class of the society who worship God and make all the religious and spiritual rule and regulation of society.

Second class was of Kshatriya who was there to fight in the battle field. They are the born warrior class of the society. Third position is occupied by traders and business person namely Vaishya class of society and the lower most class is Sudra who perform accordingly the order of the superior classes. They were untouchable class of society.

i think economic depression and disrupted trade and commerce