The most important things is that they want to know your whereabouts throughout the last 5 years.
If unemployed for a period of time, you were registered at your local job centre, then it's not a problem. They can check easily that you were on the dole then. After all, we nearly all have been jobseekers at some stage in our lifes.
If it's not the case, it's then trickier. You need somebody to back up your story about this period of your life, and, therefore you'll have to provide this person's contact details.