908. King Solomon Created Eiruvin
People who live in tents, booths or an encampment surrounded by a partition may not carry from tent to tent unless they make an eiruv. Conversely, members of a caravan surrounded by a partition do not require an eiruv and may carry from tent to tent. Their situation is already considered to be an eiruv by virtue of its temporary nature.
King Solomon enacted the rule of eiruv so that the people would not err, thinking that just as it is permitted to carry from courtyards to streets in a city and to carry to a courtyard, it must likewise be permitted to carry from a city to the fields and vice versa. They would further err, assuming that marketplaces and streets - public domains - are like fields and deserts, causing them to assume that only courtyards are private domains and that there is no prohibition against transferring between domains.