• He was named after Mihdí, Bahá'u'lláh's elder full brother, who was dear to Him and who had recently died. In later years Bahá'u'lláh gave Mírzá Mihdí the title "the Purest Branch."
• In January of 1853 Bahá'u'lláh and His family left Tehran on the first stage of their exile. Mírzá Mihdí, who was unwell at the time and unfit to undertake three months of hard travel across the Iranian Plateau and the Zagros Mountains in severe winter weather, had to be left behind in the care of relatives. The Research Department of the Universal House of Justice, which has no definitive information on the topic, suggests that it is possible that more than one relative may have cared for Mírzá Mihdí over the seven years before he rejoined his parents in Baghdad. RoL165 says that he was left with his maternal grandmother, CH45 says it was his maternal great-grandmother, BKG13 says it was his paternal aunt, Hadrat-i-Ukht, identified as Sárih Khánum.
• He was reunited with his parents in 1860 after Bahá'u'lláh's return from the mountains of Sulaymaniyah and the family remained in Baghdad for another three years, until April 1863.
• Mírzá Mihdí accompanied Bahá'u'lláh in His successive exiles to Istanbul, Edirne, and, finally, to Akka.
• Despite his youth, Mírzá Mihdí was accustomed to hardship and was recognized as "a pillar of strength" among the exiles during the difficult period after their departure from Baghdad. He resembled 'Abdu'l-Bahá in appearance and character and was noted for his piety, gentleness, dignity, courtesy, and patience. Throughout his brief adult life, Mírzá Mihdí was Bahá'u'lláh's companion and served as one of His secretaries, recording the sacred tablets that He revealed. Many such manuscripts in Mírzá Mihdí's excellent handwriting are extant." [Bahá'í Encyclopedia]
• See also Mírzá Mihdí: The Purest Branch by Boris Handal published by George Ronald Publisher, 2017
• See 22 June 1870 and 23 June 1870

Mullá Husayn proceeded to Mashhad and built a `Bábíyyih', a centre for the Bábís, as instructed by Quddús. He and Quddús took up residence in it and began to teach the Bábí religion.

Bahá'u'lláh, who hosted and directed the event, rented three gardens, one for Quddús, another for Táhirih and the third for Himself. [Bab168; GPB31, 68; MF200]

The conference coincided with the removal of the Báb to Tabríz for interrogation in July. It was held near the village of Sháhrúd in Semnan province. [BBRSM23; DB292]

Táhirih was arrested and was later taken to Tihrán where she was held in the home of Mahmúd Khán, the Kalántar of Tihrán, until her martyrdom in August 1852.

Mullá Husayn left the army camp near Mashhad where he had been a guest of a brother of the Sháh. He planned to make a pilgrimage to Karbalá. While making preparations for the journey he received a Tablet from the Báb instructing him to go to Mázindarán to help Quddús, carrying a Black Standard before him. He was also instructed to wear the Báb's own green turban and to take the new name Siyyid `Alí. [Bab171; BKG50; DB324; MH174]