问托福听力里的一个句子的结构

lilyeulogisticUID: 3482493

Now the earliest forms of advertising going back many hundreds of years with a simple sign over shop doors that told you whether the shop was a bakery, a butcher shop or what have you. 这里面的that指代的是the earliest forms of advertising吗，这是什么现象啊

hj1313UID: 3476105

that 指代的是 simple sign over the doors.