"The Yemenite girl was often engaged to be married before she was twelve years old, and she was not able to choose her future husband. When young children were orphaned, there was a danger that the Yemenis might force their conversion to Islam and remove them from the Jewish community. Thus, marriages of very young people were often arranged to prevent this tragedy. However, it appears that young girls lived with their husbands only after they matured. Marriage to older men was not unknown, and neither was polygamy. The major circumstance leading to polygamy was the practice of*levirate marriage*(a religious obligation to marry the wife of a brother who died without issue), which was encouraged among Yemenite Jews even into the twentieth century. Following her wedding, the bride moved to her mother-in-laws house where she joined the pool of female workers, continuing the same arduous tasks that she had been trained for by her own mother."
Yemen and the Yishuv | Jewish Women's Archive
But it is interesting reading also how the Jews of Yemen followed the practice of levirate marriage, that is discussed in the Mishnah verses I cited earlier, in addition to having their daughters enter into child marriages.
The reason for this practice is right there in the quote: to prevent the abduction and forced conversion of orphaned girls.
Of course there are hardly any Jews left alive in Yemen.
Yemeni Jews secretly airlifted to Israel | Jewish Telegraphic Agency