Kālidāsa
The most popular theory is that Kalidasa flourished during the reign of Chandragupta II, and therefore lived around 4th-5th century CE. Several Western scholars have supported this theory, since the days of William Jones and A. B. Keith. Many Indian scholars, such as Vasudev Vishnu Mirashi and Ram Gupta, also place Kalidasa in this period. According to this theory, his career might have extended to the reign of Kumaragupta I (r. 414 – 455 CE), and possibly, to that of Skandagupta (r. 455 – 467 CE).
Vikramaditya
There is no historical evidence indicating that the nine scholars were contemporary figures or proteges of the same king. Vararuchi is believed to have lived around the third or fourth century CE. Although Kalidasa's lifetime is debated, most historians place him around the fifth century; Varahamihira is known to have lived in the sixth century. Dhanavantari was the author of a medical glossary (a nighantu), but his lifetime is uncertain. Amarasimha cannot be dated with certainty either, but his lexicon uses works by Dhanavantari and Kalidasa; therefore, he cannot be dated to the first century BCE (Vikramaditya is said to have established an era in 57 BCE). Little is known about Shanku, Vetalabhatta, Kshapanaka and Ghatakarpara. Some Jain writers identify Siddhasena Divakara as Kshapanaka, but this is not accepted by historians.