The Indian Ocean - Michael Pearson [22]
One useful way to conceptualise land/sea relation and connections is Jean-Claude Penrad's useful notion of ressac, the three-fold violent movement of the waves, turning back on themselves as they crash against the shore. He uses this image to elucidate the way in which the to-and-fro movements of the Indian Ocean mirror coastal and inland influences which keep coming back at each other just as do waves.7
What we find on most of the shores of the Indian Ocean for most of history is a peasant agricultural economy inland interacting and connecting with a fishing and trading economy on the coast, yet it is the inland which is economically and socially dominant. Indeed, it could be argued that sea travel is unnatural for our species. Once early life came ashore and became land based, walking became the 'natural' means of getting about, not travelling over water. Over time people developed an extensive network of land communication in Eurasia; these were the essence of communication, but at certain places they intersected with the sea, and land routes were extended or duplicated by sea passages. There were intricate connections between land caravans and sea trade, or today between railways and container ships: indeed the containers are merely moved from a sea form of locomotion to a land one. Also today, sea and air sometimes intersect, so that travellers going on a cruise will often fly to meet their liner in some convenient port. Over all of history land transport and sea transport were often reciprocal, sometimes competing, and sometimes alternatives.
Sea travel has both advantages and problems. It was recognisably more dangerous, both for cargo and people, than land travel, as reflected in insurance rates, which were several times higher for sea travel than for land. Yet before steam as a general rule sea traffic was far more cost effective than that overland. Chittick claimed that one needs, roughly, the same energy to move 250 kg on wheels on a road, 2,500 on rails, and 25,000 on water.8 Similarly, it has been calculated that a dhow can travel the same distance as a camel caravan in one-third the time; each boat could carry the equivalent of 1,000 camel loads, and only one dhow crew member was needed for several cargo tons, as compared with two or more men for each ton in a camel caravan.9 So far so good, yet this refers only to technological factors. There are many others, such as politics, piracy, and the nature of the land terrain as compared with the hazards of the voyage. 'The "lubricant" required to ease as much as possible the "friction" of passage by land is as much a matter of social engineering as of communications technology.' Certainly travel by sea
was 'cheaper' in human terms, and developed much sooner, not just because of energy requirements, but because at sea the incidental hazards of negotiation, protection-money, wilful obstruction and downright violence were so much rarer than in the carrying of goods across region and region, through settlement after settlement, by land.10
Horden and Purcell note that the relativities vary from place to place. Arguably, because of the land terrain, it is easier to move goods by sea in the Mediterranean area than by land,11 but this would not necessarily apply in other seas.
Land and sea routes are often reciprocal, but they can also compete, or act as alternatives. When pipe lines are blocked