Traditionally, meats were smoked as a means to preserve them. Modern home refrigeration has only been around since 1913. Before that, people needed a way to keep food from spoiling before it could be eaten.
In a large pot, bring the water, salt, brown sugar, garlic, mustard seeds, coriander seeds, and bay leaves to a simmer. Whisk until the salt and sugar are completely dissolved.
Remove the ham from the liquid and discard the brine. Place the ham on a wire rack set inside a large roasting pan and place in the refrigerator, uncovered, overnight to air dry.