Muhammad Muradyab Khan was the eldest son of
Mian Nur Muhammad. His brothers included
Khudadad Khan,
Ghulam Shah, and
Muhammad Atur Khan. Atur Khan was his full brother, both sharing the same mother. In 1732 (1145
AH), Muhammad Muradyab was married to a daughter of Murad Ali Khan, a cousin of the
Khan of Kalat. At some point, he also became married to a daughter of the
Imam of Muscat. After
Nader Shah captured
Kandahar in 1737 (1150 AH), he planned to go through Sindh on his way to India. He had sent notice of this plan to Mian Nur Muhammad, who then sent Muhammad Muradyab to secure
Thatta while he himself went to secure
Ladkanah. Muhammad Muradyab arrived at Thatta at the end of
Dhu al-Qadah, 1151 AH (1738 CE). However, at the same time the Jam of
Kakrala and the Rana of
Dharajah brought armies to oppose him. Eventually, Muhammad Muradyab's forces drove them off with artillery, then gave pursuit until they surrendered. At the beginning of
Shawwal, 1152 AH (1739 CE), Muhammad Muradyab left Thatta and went with his father to the fort of
Umarkot to ride out Nader Shah's invasion. However, Nader Shah himself showed up and Mian Nur Muhammad, caught unexpected and concerned that Nader Shah would think he was running away, surrendered and went with Nader's camp to Ladkanah. After a payment of one million
rupees, Nader Shah confirmed Mian Nur Muhammad and went on his way, but he kept Muhammad Muradyab and Ghulam Shah as hostages. Atur Khan was later sent to join them. After Nader Shah was assassinated in 1747, Muradyab left
Tehran to return to Sindh while his brothers remained in Iran. His route took him through
Muscat, which he reached by 1750 (1163 AH), when news of his arrival there reached Sindh. Meanwhile, his companion Shaikh Ghulam Muhammad had died. When Mian Nur Muhammad learned of this, he sent the late shaikh’s brother Shaikh Shukrullah to Muscat to bring Muradyab home, but he died on the return voyage. The two shaikhs had been the last scions of a renowned
Shi’i religious family, and their deaths had a strong impression on the Shi’i community in Sindh; the poet
Muhammad Pannah Reja wrote a poem in their memory, comparing their deaths to the martyrdom of
Ali’s sons
Hasan and
Husayn. When Muradyab finally returned to Sindh in 1753, Mian Nur Muhammad received him "with great affection" and appointed him to be in charge of the state's finances, giving him the
daftar and appointing him
wazir. This was an important step in establishing Kalhoro independence after Nader Shah’s invasion because the previous wazir,
Gidu Mal, had been based at the Iranian court. However, Muhammad Muradyab turned out to be an incompetent administrator and was soon removed from office. Meanwhile, his younger brother Khudadad Khan had been the heir apparent during Muhammad Muradyab's absence, and now that Muhammad Muradyab was back, he had to resign that position; annoyed and embarrassed, Khudadad Khan ended up travelling to
Hindustan. ==Accession as monarch==