The tertiary sector is dependent on the primary and secondary sectors as follows.
1. A vital part of the tertiary sector is trade. Trade involves the sale of agricultural and manufactured goods that are produced by the primary and secondary sectors respectively. Hence, without the primary and secondary sector, trade cannot exist.
2. Another important part of the tertiary sector is transportation of goods. Such goods are ​produced by the primary and secondary sectors. Without these two sectors, the transportation sector would not exist.