What i cant understand is do death certificates start being recorded at a certain time in history?
Statutory recording of births, deaths and marriages became mandatory by law in Scotland in 1855. Prior to that one had what are now called the Old Parish Records (OPRs). Both the Statutory and surviving OPRs are available online at Scotlands People for a modest price.
Prior to 1855 there were no birth records, only the baptismal records kept by the kirks. However, as many as one third of baptisms are estimated not to have been recorded in the Kirk records. For example, one had to pay to be entered in the register so many baptisms are not there as the parents couldn't afford to pay the fee. That doesn't mean the children weren't baptised, just that the baptism wasn't recorded.
Same for marriages. Furthermore, Scotland had a tradition of what the Kirk referred to as irregular marriages and those would not have been entered in the records. There are relatively few deaths recorded in the OPRs.
If you don't find an OPR record for your ancestor, it doesn't mean that he wasn't born, married or died in a parish; just that there is no parish record of him in that parish.
