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
According to several later legends—particularly Jain legends—Vikramaditya established the 57 BCE era after he defeated the Shakas and was defeated in turn by Shalivahana, who established the 78 CE era. Both legends are historically inaccurate. There is a difference of 135 years between the beginning of the two eras, and Vikramaditya and Shalivahana could not have lived simultaneously. The association of the era beginning in 57 BCE with Vikramaditya is not found in any source before the ninth century. Earlier sources call this era by several names, including "Kṛṭa", "the era of the Malava tribe", or "Samvat" ("Era"). Scholars such as D. C. Sircar and D. R. Bhandarkar believe that the name of the era changed to Vikrama Samvat during the reign of Chandragupta II, who had adopted the title of "Vikramaditya" (see below). Alternative theories also exist, and Rudolf Hoernlé believed that it was Yashodharman who renamed the era Vikrama Samvat. The earliest mention of the Shaka era as the Shalivahana era occurs in the 13th century, and may have been an attempt to remove the era's foreign association.