The first recorded conceptualization of orientation that took into account split attraction was in 1879 by Karl Heinrich Ulrichs, a German writer who published 12 books on non-heterosexual attraction. In these books, Ulrichs has presented several classifications that are quite similar to modern LGBTQIA+ identities. Among his works, he described people who are “konjunktiver Uranodioning” and “disjunktiver Uranodioning” or conjunctive bisexuality and disjunctive bisexuality. The former is described as having tender and passionate feelings for both men and women, which would be a biromantic bisexual in modern times. The second is one who has tender feelings for people of the same gender/sex, but 'in love' feelings for people of a different gender/sex, which would now be a heteroromantic homosexual. However, the Ulrichs model never became popular due to the complexity.
