The major headache that gangsters faced was that the money was in cash, often in small denomination coins. If the coins were put into the bank, the questions would be asked. But the storage of large amounts of money in low value coins is a storage nightmare. He explains how the abuse of merchants and others by rulers led them to find ways to hide their wealth, including ways of moving it around without it being identified and confiscated. Money laundering in this sense was prevalent 4000 years before Christ.
Money laundering means different things in different places.
Also, many countries have restricted the classification of crimes that are regarded as underlying crimes for money laundering purposes. A further twist is that some countries will allow a person to be prosecuted for laundering the proceeds of criminal conduct overseas, provided the conduct would have been criminal conduct in both countries. The final point here is that in most countries that have counter-money laundering laws, a person can be guilty of the offence of laundering the proceeds of someone else's criminal conduct.