Justice Roberts references the Aztecs, Kalahari Bushmen, the Han Chinese and the Carthaginians in his dissenting opinion on the right of Gay Marriage:
The majority’s decision is an act of will, not legal judg- ment. The right it announces has no basis in the Consti- tution or this Court’s precedent. The majority expressly disclaims judicial “caution” and omits even a pretense of humility, openly relying on its desire to remake society according to its own “new insight” into the “nature of injustice.” Ante, at 11, 23. As a result, the Court invali- dates the marriage laws of more than half the States and orders the transformation of a social institution that has formed the basis of human society for millennia, for the Kalahari Bushmen and the Han Chinese, the Carthagin- ians and the Aztecs. Just who do we think we are?
I find that to be a strange dissent for obvious reasons:
The Kalahari Bushmen (*)
Many Kalahari marriages are actually monogamous, Justice Roberts is right there. But at that point his choice of examples begins to fray. Most Bushmen marriages are actually arranged marriages by senior members of that individuals kinship group. For the Bushmen it is preferred to marry cousins.
So while some bushmen do practice monogamy it is through arranged marriages with cousins.
(*) Roberts does not make it clear which group of the San/Bushmen he is referencing. Is it the: ǃKung, ǀXam, ǂKhomani, Nusan (Nǀu), Khwe (Khoi, Kxoe), Naro, Haiǁom, Tsoa, Auen, Kua, Gǀui and Gǁana?
Really one need look no further than the founding of Carthage to get a feel for where Roberts is drawing upon them for a fine moral influence.
According to Justin (Marcus Junianius) The king of Tyre, King Belus, had two children who he bequeathed his throne too. Elissa/Alissar who became known as Queen Dido and her brother King Pygmalion. Being a close family Queen Dido marries...her uncle Acherbas (Sychaeus) the High Priest of Melqart. Long story short Pygmalion kills Acherbas Queen Dido goes on to found Carthage, the city of lights.
But she married her uncle. So yes, she was technically monogamous, but still, it was her uncle.
Traditionally the Han, and other Chinese groups might have practiced monogamy superficially but ideas like polygamy, multiple equal with equal status, concubines were not explicitly forbidden and were often practiced, usually limited more by the wealth of an individual as opposed to social impropriety. The only possible exception is that the Han did consider polyandry (a woman having multiple husbands) to be immoral. They also actively practiced arranged marriages and class based endogamy!
When ever I am looking for an example to make my morally upright point in a landmark case I turn to my old friend the Aztecs. While their marriage traditions do lend themselves to the quaint vernacular of "Tying the knot" as a symbol of marriage. The marriages were arranged marriages, often using an intermediary called ah atanzah could include relatives. And while most Aztecs appear to have been monogamous, that really seemed to be more a function of class than moral values as it is well documented that kings could have multiple wives.
I am not an expert on any of these cultures and if you find any errors, drop me a note. But ultimately the point is that these societies Robert's is citing almost universally engage in pre-arranged marriages, frequently encourage intermarrying among relatives, and often engage - when economically feasible - in polygamy. All of these things which run counter to his idea of the American interpretation of the "institution" of marriage.
You can read Justice Robert's Dissent here as well as the complete ruling:
OBERGEFELL ET AL. v. HODGES, DIRECTOR, OHIO DEPARTMENT OF HEALTH, ET AL.