In 92BC, two superpowers of the ancient world met for the first time. Heading the Roman delegation was Lucius Cornelius Sulla Felix, better known as Sulla. From Parthia came Orobazus, representing Mithridates II, the King of Kings. The meeting took place near the Euphrates River held by Parthia.

The two sides were to discuss how to settle for the kingdom of Cappadocia – a buffer state between the giants. Sulla, the future dictator of Rome, ordered three chairs to be brought out – one for the king of Cappadocia, one for Orobazus and one for himself. Sulla sat himself in the middle. The talk was smooth and atmosphere amiable. The summit ended with Rome and Parthia pledging friendship to each other. Orobazus returned to Mithridates with good news. After hearing his envoy’s report, Mithridates had him executed.

By letting Sulla sit in the middle and chair a meeting that took place on Parthian territory, Orobazus had allowed a blatant breach of the sacred diplomatic protocols. The Romans would come to believe that Parthia was an easy pushover, Mithridates believed, and they would not respect the agreements.

Suspicion between the two sides grew after the incident. Rome continued to act aggressively. A series of clashes broke out between them, erupting into a full-blown conflict in 54BC that continued through the Roman and Sassanid Persian empires. The wars lasted a staggering 719 years.

It’s to be hoped things are going somewhat better as Chinese President Xi Jinping (習近平) meets his US counterpart President Donald Trump at the latter’s Mar-a-Lago resort in Florida today and tomorrow. Centuries may have lapsed, but protocol is as important to the Chinese leaders as it was to the Persian kings. The fact that Trump is a president who openly shows his disdain for the language of diplomacy and has a penchant for surprises makes this interesting to watch.

There are few human endeavours where protocols and rituals are given such importance as in diplomacy. Historian Douglas Brinkley once remarked that while the public likes to imagine the high-stakes world of diplomacy as exciting and rough, “it is more often than not a procession of suits and summits, protocol sessions and photo ops”.

For a meeting as important as this one, the two sides have done weeks of intense negotiations beforehand. As Xi and Trump sit down in the meeting hall of Mar-a-Lago, both well understand the positions and bottom lines of the other side. There is room for haggling, but rarely does such a meeting produce a major breakthrough.

The joint statement to be issued after the conclusion of the talks is likely to be vague and imprecise, as details need to be kept secret. It will take months, if not years, for the impact to be fully understood. This leaves us with some heavily scripted events, but the personalities of Xi and Trump and their approaches to diplomacy can still provide the media with much to talk about.

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Both are strong-willed men who like to lead the conversation. Trump carries his well-honed reality-TV style to politics and often uses it to bamboozle the media and political opponents, diverting their attention to where he wants it to be to gain psychological advantage. He deliberately breaks from protocol to throw off his counterparts – often career politicians who have grown too comfortable with procedures and rules. The world is still talking about his 19-second handshake with Japanese Prime Minister Shinzo Abe, patting and pulling the leader’s hand in front of the cameras. It resembled more of a tug-of-war than a courtesy greeting. Trump did so for perception management.

Body language experts will tell you that the back of your hand is your intimate zone. When you tap the back of somebody’s hand, you are portraying yourself as his senior and are offering protection and assurance to him. Often you see a grandfather doing this to a child or a teacher to a student; it is certainly not common between two grown-ups. For the infamous handshake, Trump used subtle body language to project a message that would otherwise be difficult to convey in the parlance of diplomacy – “I’m your big brother”.

Xi, however, dominates conversations with a very different style. He adheres to protocols but is not as rigid as his predecessor Hu Jintao (胡錦濤). Xi speaks in a firm and controlled tone. His meetings are fastidiously prepared, ensuring the Chinese leader has full mastery of the subject matter. He has a sharp intelligence and a natural-born calmness about him. Former US secretary of state Hillary Clinton described him as “political in the kind of generic sense of that word” and said he was “more sophisticated, more effective” than his predecessors. “You can see him work a room, which I have watched him do. You can have him make small talk with you, which he has done with me.”

The meeting at Mar-a-Lago puts these two very different characters in a room for the first time and gives them an opportunity to size each other up. A lot is at stake. With an all-important power reshuffle just around the corner, the Chinese president can ill afford an “Abe moment”. The Chinese have arrived at the meeting naturally disadvantaged – playing an “away game”. Some had hoped the summit could be held on the sidelines of the G20 summit in Germany, which would have provided a neutral ground. But the Americans allegedly told Beijing that Trump would not make the trip.

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To make it look less like Xi was seeking an audience with Trump, the Chinese side meticulously arranged everything. The trip to Florida became a stopover for the Chinese president on his way home after visiting Finland – the first such visit by a Chinese leader in 22 years. The Chinese side reportedly declined a proposal to go to Washington, picking Mar-a-Lago as the venue to avoid making the summit seem overly “official”. Xi was also said to have refused an invitation to play golf with Trump and picked his own place to stay. All these actions and preparations are meant to project an impression that the Chinese side is taking the initiative.

The world is watching closely to see how these two powerful men interact. The Mar-a-Lago meeting is one of a kind. Yet like all major international events, form is almost as important as substance.

Chow Chung-yan is executive editor of the South China Morning Post, overseeing daily print and digital operations