After Guan Yu's careless loss of Jingzhou, Liu Bei was conceited and defeated Yiling, and Shu was greatly weakened. It took Zhuge Liang five years to gradually stabilize the internal situation in Yizhou. Within five years, Shu did not send a single soldier to invade the Cao-Wei border. The border between Cao and Wei has been in a relatively comfortable state for a long time, and the defense has gradually relaxed.
In the spring of 228 AD, Zhuge Liang Bing went out of Hanzhong and took Cao Wei by surprise. And successfully won Nan 'an, Anding and Tianshui counties in Longyou area. Since then, a series of wars have broken out between Wei and Shu around Tommy Tam, the most famous of which is the "Battle of the Street Pavilion".
To answer this main question, we must first understand two points:
First, the strategic goal of Zhuge Liang's first Northern Expedition
In fact, the strategic goal of Wei Yan's "Wonder of Woods Valley" is the Guanzhong area of Cao Wei. Many people think that Zhuge Liang rejected this plan because the tactical planning of this plan is not accurate enough and the risk is too great. In fact, there is not much problem with Wei Yan's Woods Valley itself. This involves a strategic issue. Zhuge Liang and Wei Yan have different strategic orientations.
Shu's strength is weak, its strength is seriously insufficient, and there is no backup team at all. And logistics work can't be guaranteed. However, in Guanzhong area, the soldiers are fierce, the defense system is complete and the backup force is sufficient. The most important point is that the national policy before Cao Wei was originally to take risks as the defense, recuperate and win with national strength. If we rashly invade Guanzhong, it would be tantamount to forcing Cao Wei to give up the national policy of sticking to the dangerous pass and recuperating, and then sending troops to fight against Shu.
So! Zhuge Liang's strategic goal can only be locked in the relatively remote Longyou area.
Second, after taking Longyou, Zhuge Liang's next strategic planning and direction.
The national strength of Shu is far less than that of Cao Wei, and it is far from the strength to launch a decisive battle with Cao Wei. Therefore, Zhuge Liang's strategic plan is to nibble away step by step, support the war with war and fight for a long time. The most important thing is to fight for a long time because the Shu Road is difficult to travel and it is difficult to go to the sky. The Shu army has natural geographical restrictions, and it is the biggest problem that plagues the Shu army that grain and grass are not escorted.
He just needs to annex Longyou area, build a platform for the Northern Expedition in Longyou, and solve the problems such as the difficulty of the Shu Road and the lack of food and grass guards. After stabilizing the situation in Longyou area, either travel to Liangzhou in the west or overlook Guanzhong. This is Zhuge Liang's long-term battle plan.
So what? What is his next strategic goal after taking Longyou?
I think it is Liangzhou. As mentioned earlier, Guanzhong area is the hinterland of Cao Wei, with fierce soldiers, anti-essence and continuous support. It's not easy to break the Guanzhong. With the current national strength of Shu, it is certainly impossible to really fight against Cao Wei. Therefore, I think that even if Zhuge Liang unified Longyou counties, his next strategic goal will not be Guanzhong.
He should lock his next strategy in Liangzhou, which is remote, short of soldiers and without any support. It will be much easier to break into Liangzhou. In addition, Shu Han coveted Liangzhou for a long time, and he wanted to win Liangzhou when Liu Beichu got Yizhou. At that time, Sun Quan sent messengers to recover Jingzhou, and Liu Bei said that he was plotting Liangzhou. Although it is Liu Bei's excuse, it does not rule out that winning Liangzhou is his true inner thought.
So! No matter from which angle, Zhuge Liang did not dare to get his hands on the Guanzhong area of Cao Wei easily. The gains and losses of Jieting Pass are not enough to pose a threat to Chang 'an.