1. This is the full tracking of your parcel:
China Post Register Air Mail Tracking System

Parcel No.RS153884178CN tracking result
2016-07-12 21:33:29.0 parcel center received
2016-07-12 22:31:26.0 parcel center customs scan
2016-07-12 23:17:57.0 leaving parcel center ，next station Shenzhen center
2016-07-13 00:36:09.0 Shenzhen Transit Station export security scan
2016-07-13 12:37:16.0 Shenzhen Transit Station export customs scan (domestic transit )
2016-07-14 13:01:44.0 Guangzhou Transit Station export security scan
2016-07-14 15:09:01.0 Guangzhou Transit Station export customs cleared
2016-07-15 21:58:00.0 arrive Guangzhou Airport
2016-07-15 22:00:57.0 leaving Guangzhou Airport going to next airport/seaport
2016-07-18 01:14:28.0 Guangzhou express 公司 safety check rejected
2016-07-20 04:11:00.0 arrive Guangzhou Airport
2016-07-20 04:11:40.0 leaving Guangzhou Airport going to next airport/seaport

2. As you ca see there has been a safety check rejected on your parcel on the 18 July. This mean there was something inside that trigger the security check.

3. Now that said, you need to wait at least 15 days for no tracking of your parcel to make sure it departed China for your country Saudi Arabia.

4. Also please take note of this:
China Post Airmail Parcel Estimate Arrival Time for Saudi Arabia
On this site:
http://track-chinapost.com/China_Post_Arrival_Time_Stat.php

Hope this help.

Quote from Mohammed Farid1 on August 1, 2016, 12:46
Thanks for your reply
15 days count from 20 July or from today and it's actually left China or still in China

1. 15 days count from 20 July no tracking means parcel left China.

Hope this help.