Marriage is one of the oldest institutions in Ireland. The earliest legal codes in Irish history incorporated a detailed set of regulations on the rights and responsibilities of husbands and wives. In the medieval period, marriage was at the core of the conflict between Gaelic and English customs and social practices. Marital alliances were also an essential element in sixteenth- and seventeenth-century political and economic networks. The continuing significance of family connections is also evident in eighteenth-century Irish political life. In the nineteenth century, the financial arrangements for marriage were an important factor in the economic structure of rural society. Marriage also set the parameters for the sexual moral code that prevailed in twentieth-century Irish society.