A Wanderwort (plural Wanderwörter, German for "wandering word" ) is a word that was spread among numerous languages and cultures, usually in connection with trade, so that it has become very difficult to establish its original etymology, or even its original language. The separation of wanderwörter from loanwords is not unambiguously possible, and they may be considered a special class of loanwords.
Typical examples of wanderwörter are sugar, ginger, copper, silver, cumin, mint, and wine, some of which can be traced back to Bronze Age trade.
Tea, with its maritime variant tea and Eurasian continental variant chai (both variants have entered English), is a very illustrative example whose spread occurred very late in history: tea is from Hokkien, specifically Amoy, from the Fujianese port of Xiamen, hence maritime, while cha (whence chai) is used in Cantonese and Mandarin. See Tea: etymology and cognates for further details.
Another interesting example is orange, which originated in a Dravidian language (likely Telugu or Malayalam), and whose likely path to English included, in order, Sanskrit, Persian, possibly Armenian, Arabic, Late Latin, Italian, and Old French. See Orange: etymology for further details.
Also noteworthy is the word arslan (lion) of Turkic origin, whose variants are now widely distributed from Hungarian, Russian, Manchu to Persian, although merely serving as personal names in some languages; used as Aslan in the English novel series The Chronicles of Narnia.
Some ancient loanwords are connected with the spread of writing systems, an example would be Sumerian musar, Akkadian musarum 'document, seal', apparently loaned to Proto-Indo-Iranian *mudra- 'seal' (Middle Iranian muhr, Sanskrit mudrā). Some even older, late neolithic, wanderwörter have been suggested, e.g. Sumerian balag, Akkadian pilakku-, or PIE pelek'u- 'axe'. However, Akkadian pilakku- really means 'spindle', and Sumerian balag is properly transcribed balaĝ (ĝ stands for [ŋ]), means 'a large drum or harp' and was borrowed into Akkadian as balangu-.[1]
A similar, more recent example is kitab "book", originally from Arabic and now spread to nearly every language in historical contact with Islamic traders, including (among others) Swahili, Persian, Turkish, Hindi and Indonesian.