Since the chaos of the late Han Dynasty, social order had severely deteriorated, with rampant arson, killing, and looting. To protect their lives and property, wealthy families with means had to organize their own armed forces and defensive installations, while those without means sought refuge by gathering near powerful households. This way of life persisted for centuries. The rise of "prominent noble clans" mentioned earlier was directly related to this phenomenon—many residences of local powerful families were built according to military fortress requirements.
The early Tang Dynasty marked the end of these centuries of turmoil, though people at the time didn't realize it and still lived with the mindset of a chaotic era. Important detached palaces, noble estates, and the like generally had defensive facilities like stockade walls and corner towers. Since the Temple of Common Vocation was originally Prince Qi's residence and located in the relatively desolate forbidden garden, it would have been strange if it didn't have blockhouses for patrols. Later in the story, the Great Peace Palace (Prince of Qin's Manor during the WuDe Era) also features these same facilities.
The image below shows a pottery model of a Wu Kingdom-era estate displayed at the National Museum. It has a gate tower above the main entrance and corner towers at each corner of the perimeter wall, housing inhabitants—a typical fortified noble residence. Excavated in Echeng, Hubei in 1967. (Please visit the author's Weibo to view the image.)
Simply put, it means "beginning an official career and entering government service." Here, "coarse cloth" symbolizes "commoner's clothing." Under normal circumstances, noble offspring in the Tang Dynasty weren't born with official positions—even sons of princes and princesses, despite their high hereditary privileges, had to go through certain selection processes upon reaching age. Most began their official careers by serving in the "Three Guards."
The "Three Guards" collectively refer to the Imperial Guard, Merit Guard, and Winged Guard—all being ranked imperial bodyguard positions. Sons of third-rank officials or grandsons of second-rank officials could compete for the "Imperial Guard" position (upper seventh rank) after turning 21. Grandsons of third-rank officials and sons of fourth-rank officials could compete for the "Merit Guard" position (lower seventh rank), while sons of fifth-rank officials could compete for the "Winged Guard" position (upper eighth rank). During the Zhenguan era, the Three Guards were still prestigious and valued positions, but this declined after Emperor Gaozong's reign.
#####This book contains numerous historical artifact images in its annotations. As the publishing platform doesn't support image functions, please visit the author's Weibo to view them. Search for "Tang Dynasty Travel Guide Forest Deer" on Sina Weibo. Discussions welcome. ????