Consider the following statements about the rule of Shakas, Parthians, and Kushanas in Punjab:

1. The Shakas established Takshashila (Taxila) as their capital, making it one of their five major centers in India.

2. Parthian king Gondophares, who ruled Punjab, is linked to early Christian traditions that claim Saint Thomas visited his court.

3. The Kushanas were the first rulers in India to issue gold coins extensively, showing their wealth and trade connections.

4. Roman coins found in Punjab suggest that the region had extensive trade ties with the Roman Empire during Kushan rule.

Which of the above statements are correct?