Beginner: Where are data stored?

Hi all,

i am a beginner at SAP and the SAP Business Suite. I would know how SAP handle the data storing between SAP-MDM and ERP. If i import catalog informations for procurement processes into SRM-MDM and create a order transaction, where will saved the article informations? As a reference ERP -> MDM or full replicate (copy) of the dataset?

Thx in advance

H.Mayer