Mori Yihya Kapach, the Elder Mori, son of Shlomo (Sleiman), was born in 1850 in Tsana'a, Yemen.
His mother died when he was a year old, and his father remarried. When he was eight years old, his father Shlomo died. Mori Yihya Kapach was raised in his grandfather's home, who was entirely devoted to him despite his poverty, and studied with Mori Haim Korach and Mori Yosef Elkarah.
Mori Yihya Yosef married Ni'meh; he worked as a silversmith and she worked as a seamstress and in embroidery. The family lived on a pittance, and not all their children survived; two of them died in the great famine of 1905. They were left with a son and two daughters.
Mori Yihya Kapach was one of the founders and leaders of the Dor De'ah Society which was active in Yemen at the time, principally in Tsana'a. Its members, known as the Darda'im, sought to bring the Yemenite Jewish community back to the Halakhic rulings by Maimonides and Rabbi Sa'adia Gaon that preceded those of the Shulchan Aruch. They were opposed to the study of Kabbala and Zohar, and encouraged secular studies. Mori Yihya Kapach's activities with his group provoked resistance in the Jewish community. Those who opposed the Darda'im, for all that they represented a majority in the community, were labeled "the stubborn ones".
Mori Yihya Kapach, one of the Darda'im's leaders, and Mori Yihya Yitzhak Halevi, a leader in the community, continued to cooperate in the rabbinic court and took great care not to inflame the debate. The conflict, however, escalated to accusations, exclusions and tattling, which brought about the involvement of the local authorities in Jewish community life, out of their concern for the regime's stability.
In 1899, when he was 50 years of age, Mori Yihya Kapach was appointed Hacham Bashi, Chief Rabbi of Yemen. His term lasted only six years, after which he earned a living from teaching children at Haim Cassar's home.
In 1910, Mori Yihya Kapach was appointed principal of the Jewish school established by the Ottomans in Tsana. The school flourished, and its pupils studied Arabic, Turkish, Hebrew and sciences, as well as Jewish studies. The school was closed in approximately 1914 by the authorities, apparently because of false accusations and tattling by opponents of the Dor De'ah movement. Mori Yihya Kapach, his son Mori David Kapach, and additional members of the movement were imprisoned under suspicion of collaboration with the British, and accused of undermining public order.
The movement's activities were outlawed, including study and prayer meetings in private homes. Its members continued to meet in secret nevertheless, and would gather every Motsa'ei Shabbat for a class on Maimonides' Guide to the Perplexed given by Mori Yihya Kapach.
In 1918, Mori Yihya Kapach, aged 68 at the time, his son Mori David Kapach and additional members of the society were arrested – part of yet another wave of arrests – during a Torah class. Mori David, whose son Yosef Kapach was but a year old, was severely beaten by the policemen and badly injured by a rifle that hit his ribs. He did not recover from the injury and died from his wound.
Mori Yihya Kapach passed away on 11 Kislev 5696 and was buried in Tsana'a.
Mori Yihya Kapach collected his opinions and writings on the anti-Kabalistic approach in his book Milhamot Hashem, published posthumously. His correspondence with Hillel Tzeitlin concerning Kabbala was published in Da'at Elohim. He was known for his very concise Responsa; his written comments on Halakha concerning ritual slaughter and non-kosher foods have remained, to date, in manuscript form.