In ancient Indian chronology, which ruler is credited with starting the Saka Era that is still used in the official Indian calendar?

Introduction / Context:
Chronological eras play an important role in Indian history and in the way dates are recorded in inscriptions and official calendars. Two frequently mentioned eras are the Vikram Samvat and the Saka Era. The Government of India uses the Saka Era as the basis for the national calendar alongside the Gregorian system. It is historically associated with a particular ruler. This question asks you to identify that ruler, which is a common fact tested in competitive examinations.

Given Data / Assumptions:

• The question is about the origin of the Saka Era.
• Options include Ashoka, Samudra Gupta, Vikramaditya, Kanishka and Harsha.
• We assume standard historical association accepted in exam oriented material.
• The Saka Era begins in the first century of the common era.

Concept / Approach:
The Saka Era is generally linked with the Kushan ruler Kanishka, whose accession is placed around 78 CE in many historical reconstructions. According to widely accepted tradition, this year marks the beginning of the Saka Era. Although there are debates about exact dates and interpretations, for examination purposes the clear association is between Kanishka and the Saka Era. Vikramaditya is associated with the Vikram Samvat which starts in 57 BCE. Ashoka, Samudra Gupta and Harsha are not connected with the starting point of the Saka Era.

Step-by-Step Solution:
Step 1: Recall that the national calendar of India is based on the Saka Era. Step 2: Remember from history lessons that the Saka Era is believed to begin with the accession of Kanishka around 78 CE. Step 3: Note that Vikramaditya is associated instead with the Vikram Samvat beginning in 57 BCE. Step 4: Confirm that Ashoka, Samudra Gupta and Harsha have other achievements but are not linked to starting this era. Step 5: Therefore, choose Kanishka as the ruler who started the Saka Era.

Verification / Alternative check:
Most competitive exam guides contain direct statements that Kanishka started the Saka Era in 78 CE. School textbooks also mention that the Indian national calendar uses this era and that it is tied to Kanishka and the Kushan dynasty. Checking timelines of major dynasties and their contributions further confirms that Kanishka name alone is consistently associated with this era, providing a strong verification for the answer.

Why Other Options Are Wrong:

• Option A: Ashoka belonged to the Mauryan dynasty and is known for his inscriptions and spread of Buddhism, not for starting the Saka Era.
• Option B: Samudra Gupta was a Gupta ruler famous for his military campaigns but not connected with this chronological system.
• Option C: Vikramaditya is associated with the Vikram Samvat, a different era starting in 57 BCE.
• Option E: Harsha ruled later in the seventh century CE and did not found any major era used in official calendars.

Common Pitfalls:
A common confusion arises between the Saka Era and the Vikram Samvat because both are used in different contexts in India. Many students mix up Kanishka and Vikramaditya when under time pressure. To avoid this, remember a simple rule: Kanishka is linked with Saka and a date in the common era, while Vikramaditya is linked with Vikram Samvat and a date before the common era. Creating a small memory sentence such as Kanishka Saka can also help fix this association in mind for exams.

Final Answer:
The correct answer is Kanishka.