I will repost this question since the last one 9 months ago wasn't answered.
I will admit that I am not exactly sure how one should phrase this question and what part of what is now modern day China can be qualified for this topic, as my knowledge of early Chinese history is very limited. I suddenly realized that names, positions, relations and broad course of events concerning notable adversaries in Roman history, such as Carthage, Gauls, Germanic tribes and Parthians, are well known and researched, while I can hardly name anyone on the Chinese side during the period up to early AD, except for Xiongnu. Everybody knows that Carthage was fighting Roman republic for many years, and everybody knows that Caesar conquered Celts. What is the direct or broadly similar counterpart to these events, say, for Han empire? Who was Chinese Hannibal and what Gauls were actively resisting their conquests?
Since u/y_sengaku tagged me in and I feel guilty for nine months ago, I can provide a Later Han (25-220 AD) and early years of the civil war perspective, hopefully still within the early AD wheelhouse.
Part 1 of 4
South
As China colonized Jing and across the Yangtze, as people fled the control of the government or wars in the north, the indigenous people got pushed out towards the hills, suffered through re-education and their culture including shamanic leaders was suppressed by energetic officials.
Unsurprisingly this was sometimes met with resistance in the south of Jing with the Wuling people (sometimes called Wuqi) notable for rising up now and again. If not dealt with by commandery or provincial troops, a General might be sent but I don't recall a name feared, more that they could be troublesome. The biggest was probably the late 50's and early 60's when a series of revolts across south Jing span out of control, first local forces then imperial forces were defeated until Minister Feng Gun was made a General came with 100,000 men in 162.
Across the Yangtze were the Shanyue (southern barbarians of the hills) which comes more into focus during the civil war. With central control collapsing local notables raised forces and some, via connections to the area, could hope to pull on Shanyue support. When the Sun family, first under Ce and then after his assassination, younger brother Quan could find that local leaders like Zu Lang turned to the Shanyue for support. For the Sun clan, the Shanyue could be a useful resource of land and manpower to counter the strength of the north and China's grip expanded south under generals like He Qi. For opponents like the Cao's or their agents the Chen family, contacting unhappy people like You Tu and stirring up trouble was a way of keeping Sun forces distracted. Zhuge Ke's starvation campaign in the mid-230s cemented control up to the Zhe river.
Possibly the most well-known name of the local leaders is a leader of a coalition White Tiger Yan (thanks to name perhaps, opposing Sun Ce and made a King in the novel) but I can't think of any that struck fear into the Sun clan.
West
The Banshun were a people that the Han were happy to hire when they needed extra manpower to help settle troubles in the western regions or in Jing with a reputation as excellent fighters. However, mistreatment did see the odd flare up, in 179 they rebelled and it took an amnesty in 182 to persuade them for peace. During the civil war, the Ba area became out of control with the ineffectual Liu Zhang and the theocrat Zhang Lu competing for the area and they were able to achieve some independence, in 215 providing refuge for Zhang Lu as he negotiated surrender to the Han controller Cao Cao. They would be driven away soon after into Cao Cao's lands by Huang Quan, an officer of western warlord Liu Bei.
To the west of the fertile province of Yi was a fertile land with trade routes and a diverse people in Nanzhong who were, thanks to distance and terrain, difficult to conquer for the Chinese. Attempts to assert practical control rather than symbolic or bad officials could see difficult revolts and in 176, defeats saw some argue for abandoning the area but Li Yong would put it down. Chinese magnates like the Cuan would take control but like across the Yangtze, would have connections with the local peoples.
In 215, one such local magnate Yong Kai rebelled against the new regime of Liu Bei and allied with Sun Quan, the future Shu-Han regime struggled to put it down. His efforts expanded after the death of Liu Bei in 223 and he got the well-connected Meng Huo to bring the local people to his side then in 225, Shu-Han chancellor Zhuge Liang led forces against them. Yong Kai was assassinated in a row and despite Meng Huo's stubborn resistance, they were beaten within six months. Zhuge Liang carefully planned how to (mostly) keep the peace by keeping the magnates onside and accepting some loss of Chinese grip in exchange for manpower, their excellent horses and resources. Later Ma Zhong and Zhang Ni would aggressively campaign to expand and restore the Chinese grip in the area. When Shu-Han fell in 263, the historian and soothsayer Qiao Zhou warned they would revolt if the court fled there and tried to draw on the resources.
I mention this, despite again no real names of fear to stand out, because the novel turned Zhuge Liang's campaign into a big multi-chapter campaign where exotic human sacrificing Nanman get pacified and educated by this scholar exemplar. Because of the novel, Meng Huo becomes an unfilial Nanman King with a warrior wife Zhu Rong in strange lands with strange beings, they are most known in popular culture. A faction long in Dynasty Warriors and Total War Three Kingdoms soon had calls for the Nanman to be included.
For Later Han and the civil war, the major names and threat was to the north
North
The Later Han had a problem in the area with depopulation (which was made worse under the pressure of wars) meant Han was losing ground gradually in the north. Heavy-handed and sometimes corrupt or dishonest officials could needly provoke long-lasting and painful wars. It would be the long northern border that would be the focus of the armies and the histories.
Since they were mentioned, let us start with the old foes the Xiongnu.
Ruled by a Shanyu with his clan holding the ranks of King, the Xiongnu ruled over a range of nomadic people, skilled with archery and horse with the best food going to the strongest (similar descriptions were given to Wuhuan and Xianbei).
Once the Later Han established itself and defeated the Xiongnu allies/rival claimants with the Later Han forced to abandon some of its northern areas for a time and build walled defences on the Fen river to protect Chang'an. However, the death of the elderly Shanyu Yu around 46 CE would be the end of Xiongnu's rise as his son Wudadihou died within months and the Xiongnu leadership under Shanyu Punu was in trouble.
In ways that would keep repeating, droughts and locusts (with resulting famines) on grazing land were a disaster at home. Meanwhile, the Han constantly stirred up trouble either by encouraging attacks from abroad like the Wuhuan and the Xianbei. Or, when an opportunity arose, by encouraging discontent within the ranks which would undermine the Xiongnu leadership.
By 48, there would be two Shanyu's, a North Xiongnu under Punu and the South Xiongnu under his rival Bi. For the Han and for the Southern Shanyu, it might be considered a mixed deal. For the Han, they got an ally populating their sparsely populated frontier as they moved (in three stages) into Shoufang in Bing, someone they could oblige to bring considerable troops for defensive protection and for offensive efforts against the north. However, the subsidies would be quite expensive (by the 90s it would be 100 million cash a year) and the southern Shanyu's could be quite happy to push their own agenda on the frontier, concerns about how the Southern Xiongnu would react played a part in decision making.
For the Southern Shanyu, it was recognition of his claim to be Shanyu, the protection and support of a large power that could provide considerable support against their northern rival while free to launch attacks north. Subsidies that could be used to help keep support and maintain their position but obliged to provide support if Han requested it and moved away from their traditional heartlands.
While the Southern Shanyu did have power over his people and could have influence, the Han also found ways to assert control. For example, setting up officials in the Shanyu's camp to supervise and providing a Han-Chinese bodyguard of 50 men for "protection", a hostage was sent and rotated to the Han capital of Luoyang, and tweaks to the veneration of ancestor ceremonies were tied to venerating the Han imperial clan. Though the Southern Shanyu's would suffer various humiliations down the years from their ally, Bi for example was humiliated by being the first Xiongnu Shanyu to perform a kowtow and not even to an Emperor but to his envoys in a display of Han authority.
Raids from the north did carry on, quite aggressively in the 60s, to try and put pressure on for peace and access to frontier trade which the Han carefully controlled. While sometimes the Han was interested, even Han envoys could be reluctant to take on the task, one envoy Zheng Zhong constantly objected to the plan with constant letters so got recalled. There was also the danger for the Han of how the south Shanyu would react, feelers in the '60s saw the southern Xiongnu reach out to the North and the Han had to set up military forces including restoring the role of General of the Liao to ensure the two Xiongnu's did not ally. In 73 the Han did try a multi-pronged invasion into the steppes but the Nothern Xiongnu decided to avoid battle so it was rather ineffective.
"Chinese Hannibal"
Though I'm also really specialized in this area and in region, I suppose your first impression is basically correct: The Xiongnu and its ruler, Modu Chanyu (r. 209 BCE? -174 BCE) must have been the closest parallel, the most formidable threat to (early) Han Empire.
Unfortunately, AFAIK almost only /u/FlavivsAetivs' post in Why was Genghis Khan the only steppe ruler to conquer most of eurasia, and not other steppe rulers at any other period of its thousands year history? looks decent on Modu Chanyu and his confederate in culminated answers of this subreddit.
Modu Chanyu built up his power over other nomadic rulers (chieftains) divided by the left and right wings, and surrounded the isolated army branch of Emperor Gaozu (Liu Bang), no other than the founder of the Han Empire, in the Battle of Battle of Baideng in 200 BCE. Historian Shima Qian narrates in his Shiji (Records of the Grand Historian) that emperor of Han himself barely escaped this surroundings, by bribing one of Modu's wives (Sawada 2015: 42-48).
It was until the ascension of Emperor Wu (r. 141 BCE to 87 BCE), about a generation after the death of their prominent ruler Modu (174 BCE), that the power balance between the Han Empire was the Xiongnu confederate had kept the latter's favor. Two generals of Emperor Wu, Wei Qing (d. 106 BCE) and Huo Qubing (140 BCE-117 BCE), especially the younger latter (in fact also the former's nephew) might be compared to "Chinese Scipios".
The fate of famous historian Shima Qian himself is also somehow connected to the relationship between the Han and the Xiongnu (Have you ever heard why he was forced to live as an eunuch in detail?), but anyway, Shiji fortunately tell us a bit about the nomadic life of the Xiongnu people as well as the life of Modu, just as Herodotus writes the habits of Scythians in his Histories ([Hayashi 2017] compares the description on the Scytians in Histories Book 4 with that of the Xiongnu found in Book 100 of Shiji). It's a shame that the full English translation of Shiji, including its Xiongnu section, is not easily available online.
Since even some recent overview books on the history of the Nomads don't not always have detailed section on the Xiongnu and their rulers (at least either Beckwith or Crossley barely mention the name of Modu), you'll perhaps have to check more specific literature on the Xiongnu's activity like Di Cosmo or Markley (sorry for that neither of them I have not read in person).
Alternatively, Markley (author of one of the specific literature mentioned above) conveniently summarizes a basic outline of the relationship between the Han Empire and the Xiongnu people in the following essay: https://www.asianstudies.org/publications/eaa/archives/china-versus-the-barbarians-the-first-century-of-han-xiongnu-relations/
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