I saw there is a tag yuga & kali-yuga, but No tags for Satya yuga, treta yuga, dwaparayuga. can someone create these tags?
General tagging guideline is as follows:
A tag is a word or phrase that describes the topic of the question. Tags are a means of connecting experts with questions they will be able to answer by sorting questions into specific, well-defined categories.
As a general rule, you should avoid creating new tags if possible, and new users are not allowed to create new tags. Even if you have sufficient reputation, you should only create new tags when you feel you can make a strong case that your question covers a new topic that nobody else has asked about before on this site.
So, if you feel clear needs to create tags for questions, and have tag creation privilege, simply add tag to questions.
Visit FAQ: Can we please have the [foo] tag on our site?.
In order to create new tags, one must have existing questions deserving those tags.
If you don't have privilege for tag creation, mention questions needed to be tagged with it and give proper reasons why you think we need tags.
Here tags kali-yuga and yuga have been finding their scopes for frequently asked questions regarding it. Mention some questions that needs tag for satyuga and dwaparyuga. If there are existing (or possibility of) no. of questions (being asked) on those particular areas, it would be worth to create tags for them.