Caravaneer

Historically, caravans were the primary means of conducting large scale trade between cities. The caravaneers who operated these ventures tended to be a multicultural group, and while they never meshed particularly well with the rest of society, they performed an important function and also provided a foundation for cooperation between different countries - after all, if caravaneers from different countries can work together to foster trade, the leaders of those countries can surely settle their differences and work together for the good of all. Some now believe that, as faster forms of transportation replace them, the loss of the caravaneer may well be the first step toward a world of dogmatic nation-states that refuse to cooperate on principle...though most consider this to be alarmist, or an overemphasis on the role of caravans in fostering cooperation between kingdoms.

Decline

Over the last several hundred years, a number of technologies have been developed that have reduced the need for trade caravans. The advent of the larger ships lauded as the Age of Sail is the first of these - while caravans operating over land can usually take a more direct route than a ship sailing along the coastline, the vast cargo capacity of large ships has makes these vessels the cheapest option. Combined with the ability to reach overseas destinations, many came to see caravans as an unfortunate necessity for transporting goods from a coastal port to inland settlements.
In order to further increase the speed of trade, many countries also connected a series of canals, connecting natural waterways to produce a network of passages for shipping inland. Early canals primarily made use of towed river barges, but the development of the steam engine about 50 years after the completion of the first major canals enabled powered river boats that could move upstream against the current. While these boats have much more modest cargo holds than the sailing ships of the open sea, a steamboat with a 3 person crew can still handle a cargo that would take dozens of caravaneers.
Finally, the development of the Steam Locomotive is expected to be the final nail in the coffin for large caravans. Already restricted to mountainous regions where rivers run too shallow and too fast to safely navigate, the speed of the locomotive means that a rail line that goes around terrain too steep for a train to handle can still manage the journey in less time than a caravan of horse-drawn wagons can cutting straight through.