The Spanish Army, before the civil war broke out, had eight divisional commands in peninsular Spain, each based in a major city: Madrid, Seville, Valencia, Barcelona, Zaragoza, Burgos, Valladolid and La Coruña. Of these, only Madrid, Valencia and Barcelona remained unambiguously in Republican territory at the start of the war.

It's worth pointing out that the location of each 'division' was misleading, as individual regiments were garrisoned separately across the region. It rarely makes sense to think in terms of divisional commands in the early days of the civil war, as individual units tended to act independently of the command hierarchy. This was particularly the case in the Republican Zone, where very few of the nominally existing military units could actually be employed, not least because many of the officers' loyalties were immediately suspect. Many units were simply dissolved early on, with those suspected of actively disloyalty arrested and others simply disarmed and sent home. Even the Madrid division, the least affected by this process, only had about 10% of its pre-war strength in officers and men in late July, drawn from a mix of units scattered around the capital. This was of course in no way a cohesive force at this point, even less one that resembled a 'division'.

You might be interested in a previous answer of mine on how sides formed in the early days of the war. If you're struggling with doing research in Spanish, the major work in English on the subject is Michael Alpert, The Republican Army in the Spanish Civil War, 1936–1939 (Cambridge, 2013).