Yeah, my Bombay SSC's pop level of 43 was boosted by Food Trade Caravans (one from each city works perfectly to balence it out), not converted food squares. I left all but one of the trade squares (half of it was the himalayian mountain mines, including a gold mine, and the other was silk which I converted accidentially before I understood that irrigation would do that) as it was. Dacca only had plains and wheat trade squares when I founded it.