Bankruptcy happens when you reach -10,000 gold, at which point you immediately lose and are presented with a gameover screen. Before going bankrupt, Lord Northburgh will warn you and an info box will appear warning you about bankruptcy.
If you ever find yourself approaching -10,000 gold, it's helpful to use the slowdown mode and immediately remedy the situation by:
- Asking for "loans" (they never have to be repaid) from Lord Northburgh or Al Zahir using Honor points
- Demanding tribute from any AI players who are likely to pay you (those weaker than you)
- Quickly demolishing as many costly production buildings as possible
- Deleting non-essential ships and military units
- Raising the tax rate to maximum (the far right on the slider) on your highest civilization classes
- Actively selling all goods not absolutely required by inhabitants, such as Tools, Ropes, Glass, Mosaics, Weapons, etc.
- Settle a new island, build some fisher huts and fill up the rest with houses.