Family loyalties are greater than those between friends - many believe the origins of this expression were actually based on the opposite of today's meaning of the phrase, and there there would seem to be some truth to the idea that blood friendship rituals and biblical/Arabic roots predated the modern development and interpretation of the phrase. Various references have been cited in Arabic and Biblical writings to suggest that it was originally based on Middle- and Far-Eastern customs, in which blood rituals symbolised bonds that were stronger than family ones. 'The blood of the covenant is stronger than the water of the womb' is an explanation quoted by some commentators. However the expression has certainly been in use for hundreds of years with its modern interpretation - ie., that blood is stronger than water (relatives being connected by blood, compared to the comparative weakness of water, symbolising non-family). In this sense, the metaphor is such an obvious one that it is likely to have evolved separately from the supposed 'blood brothers' meaning, with slightly different variations from different societies, over the many hundreds of years that the expression has been in use.