raoul mclaughlin writes that this event of roman subjects visiting the han chinese court in 166 could have ushered in a new era of roman far east trade, yet it was a "harbinger of something much more ominous" instead. mclaughlin surmises that the origins of the plague lay in central asia, from some unknown and isolated population group, which then spread to the chinese and roman worlds. the plague would kill roughly 10% of the roman population, as cited by mclaughlin, causing "irreparable" damage to the roman maritime trade in the indian ocean as proven by the archaeological record spanning from egypt to india, as well as significantly decreased roman commercial activity in southeast asia. however, as evidenced by the 3rd-century "periplus of the erythraean sea" and the 6th-century "christian topography" by cosmas indicopleustes, roman maritime trade into the indian ocean, particularly the silk and spice trade, certainly did not cease and continued up until the loss of egypt to the rashidun caliphate. chinese histories also insist that further roman embassies came to china by way of rinan in vietnam in 226 and 284 ad, where roman artifacts have been found.