Going by the convo in-story at least this society is apparently fine with basically any match-up if the string says so, so there's that.
Mind you... far as we're told the string between any given pair is only visible to themselves so others will basically just have to take them at their word anyway.
EDIT: Also, you can imagine the epic cultural clashes that will occur when something like the European trade ships contacting China. When the system is worldwide, and the societies view the significance of the string differently, the resulting problems when strings start appearing across borders will be =/
IRL state borders in the modern sense didn't really even exist until about the 1800s to begin with, and only in exceptional cases do they form an insurmountable barrier to human movements. Practical economic concerns and the like are normally a rather bigger one (hence the earlier about problems of distance and the means to deal with them).
Hell.
Last I heard marrying a native is generally one of the easier ways to get naturalized.
In premodern context a far more relevant worry would be if the couple's respective relevant social units (families, clans, tribes, whatever) have some kinds of hostilities going... and I don't want to even think about what kind of sand this will throw into the gears of upper-class dynastic calculations. Probably just results in a widespread practice of adopting heirs if necessary, many IRL societies have run with that for a long time anyway.
last edited at May 8, 2018 12:24PM