Bureau asking customer to prove source of money

I recently came to Tanzania and went to a bureau de change to buy foreign currency in exchange for Tanzanian shillings. I only TZS 300,000 which I wanted to convert into foreign currency. The operator of the bureau de change asked me to give him proof of the source of TZS 300,000. Is there such a legal requirement?
PK Arusha

It is a requirement of regulation 28 of the Foreign Exchange (Bureau De Change) Regulations, 2019 [GN No.540 of 2019] that a bureau de change should not sell foreign currency to a non-resident unless the non-resident proves to the bureau de change that he obtained the Tanzanian shillings he wants to exchange with foreign currency from the previous sale of foreign currency or that he obtained the Tanzanian shillings in Tanzania from lawful activities. Under the Regulations, a non-resident is a person who has been in the country for less than twelve months consecutively.

Since you have been to Tanzania for less than 12 months, you are a non-resident hence you are bound by regulation 28. By its nature, the provision of regulation 28 was intended to act as an anti-money laundering provision against the proceeds of crimes committed by foreigners in Tanzania that is why the law does not put a threshold amount and hence the requirement that a non-resident has to prove his source of income is imposed irrespective of the amount involved in the transaction.

The bureau de change operator was acting within the law when he asked you to prove the source of Tanzanian shillings you wanted to exchange for foreign currency.