This spice blend in Bengal, in eastern India, consists of whole seeds of cumin, black mustard, fennel, nigella, and fenugreek in equal amounts. If you aren't accustomed to Indian spice mixtures, you might want to start with a smaller proportion of fenugreek perhaps one third as much as the other spices because in large quantities it adds a bitterness that some people find unpleasant.
This blend is not ground, but is heated in ghee or oil just before using to release the flavors of the seeds. The dry seeds can be stored for at least four months in an airtight container away from light and heat.