The Bhutanese societies practised barter of goods as a main form of trade before the monetised economy was introduced. Traders would buy things from their sources to be sold at another place in exchange for a thing which is produced there. They would take that produce to another place to be exchanged with another item. Leading traders often travelled with a caravan of horses and mules on their business trips. Some leading families employed their own traders, who maintained the caravan and made trips between the trade marts including those on the borders with India and Tibet.