Bureaucratization in trade unions refers to the development of formal administrative structures, specialized leadership, rules, procedures, and permanent officials within trade union organizations. Although trade unions became especially important with the rise of industrial society, their organizational tendencies can also be understood in relation to older forms of collective organization found in ancient and medieval societies. Guilds, merchant associations, craft organizations, and occupational groups often developed systems of leadership and regulation that anticipated some features of modern bureaucratic organization. In ancient societies, occupational groups and merchant associations existed in several regions. In India, guilds or shrenis brought together artisans, traders, and craftsmen. They regulated production, prices, quality, training, and commercial activities. Such organizations had leaders and established rules for their members. Similarly, in the Roman world, collegia represented occupational and social groups. These institutions demonstrate that collective economic organizations required administration, authority, record-keeping, and mechanisms for enforcing decisions. However, their structures were generally less complex than modern trade unions. During the medieval period, guilds became particularly influential in European towns. Craft guilds organized workers belonging to particular occupations, such as weavers, metalworkers, carpenters, and merchants.