I assume that you are asking about the task that was imposed upon the natives of the province of “Cicao on Haiti” by Christopher Columbus. This is discussed in Chapter 1 of A People’s History of the United States. The task was impossible because there was not enough gold in the region to satisfy Columbus’s demands. (All quotes are taken from the link below.)
According to Zinn, Columbus needed a lot of money to pay off his debts. He tried to sell slaves that he took in the Caribbean, but too many of them died. He then turned to the idea of having the natives bring him gold. He believed that there were “huge gold fields” in the province mentioned above. Therefore, he ordered all the Indians over fourteen years old to bring him some amount of gold (Zinn does not say how much gold that was). If they did not bring the gold, they would be punished by having their hand cut off.
Zinn then says that it was not possible for the Indians to do this. He says that
The Indians had been given an impossible task. The only gold around was bits of dust garnered from the streams.
Because they could not get the requisite amount of gold, they were hunted down and killed. In telling this story, Zinn is trying to support his claim that Columbus’s actions in the Caribbean amounted to genocide.