Step 1: Understand the Core Question: Identify the two principal Persian artists who accompanied Emperor Humayun back to India from his period of exile. These artists are recognized for establishing the foundation of the Mughal School of painting.
Step 2: Detailed Explanation: Following his defeat by Sher Shah Suri, Emperor Humayun sought refuge in Persia at the court of Shah Tahmasp. During this exile, he was exposed to the sophisticated art of Persian miniature painting. Upon reclaiming his throne in Delhi in 1555, he invited two preeminent Persian masters from the royal workshop to join his court. These artists were Mir Sayyid Ali and Abd us Samad. They assumed leadership of the imperial art studio and were instrumental in training a new cohort of Indian artists. This collaboration led to the fusion of Persian techniques with Indian artistic sensibilities, resulting in the distinct Mughal style. \[\begin{array}{rl} \bullet & \text{Bihzad, though a renowned Persian master, belonged to an earlier era and did not relocate to India with Humayun.} \\ \bullet & \text{Shah Tahmasp, the Safavid king of Persia, offered Humayun sanctuary. He functioned as a patron, not as an artist who moved to India.} \\ \end{array}\]
Step 3: Final Identification: The two master artists who returned to India with Humayun were Mir Sayyid Ali and Abd us Samad.