The world of Gethen is currently undergoing its ice age, so it's not exactly tourist destination number one. The weather is cold, bitter, and hard, and affects every aspect of life on the planet.
For example, the Gethenians are undergoing an industrial revolution of sorts, but it's a far slower burn than our own. We went from steam engines to the Internet in a hundred years flat. The Gethenians have used the same landboat vehicles for centuries, and they still haven't gotten off their butts to develop planes. Then again, they've got a lot on their minds just surviving the frigid climate.
Ai spends most of his time on Gethen, in cities in Karhide and Orgoreyn, so the weather doesn't affect much of the story. But when Ai and Estraven traverse the Gorbin Glacier—a.k.a. the Ice—it becomes another issue entirely.
You remember Vanilla Ice? No? Good for you.
The Ice is what you'd get if you hiked a less friendly version of Siberia. It's a landscape of volcanoes, steep cliffs, and ice crevasses. Each step could lead to injury, which would be a death sentence. (No search-and-rescue out on the Ice.)
Great. Exactly the sort of place you want to stay, oh, about 250 miles from. But Ai and Estraven must cross it if they want to escape Orgoreyn and get to Karhide. Le Guin spends a lot of time detailing the monstrous landscape of the Ice, but no sentence in the novel better sums it up than: "There is nothing, the Ice says, but Ice" (16.35).
The Ice also appears in some of the supplemental chapters. In Chapter 2, Getheren finds himself wandering the Ice, and the Orgota Creation Myth of Chapter 17 takes place on the Ice as well. All of the supplemental stories have a key theme: birth and rebirth. Same for Ai and Estraven. Their crossing of the ice means the birth of a new era for Gethen. Only if they can just, you know, not die.
Ai's first attempt to accomplish his mission takes place in Karhide. Karhide is a country with a King—King Argaven XV to be precise—and lords so the place feels very similar to Earth countries of the past. The King is in charge, so you live by his whim and rule. Thankfully, Karhide has a system of social policy called shifgrethor, which keeps the King's power in check to a degree.
Karhide is also further along in terms of social equality than our historical king societies or even other Gethenian societies. It has a democratic council that people can be voted to—Estraven and Faxe both serve their countries here. They also have the lovely policy of "no institutions of slavery or personal bondage, hire services not people" (1.72).
So, Karhide holds an interesting place in Le Guin's world. On the one hand, it seems behind the times with Kings and Lords and all, especially compared to Orgoreyn, which has done away with that stuff. On the other hand, their social interactions are far more in-line with our modern sensibilities (again, unlike Orgoreyn, which practices various forms of social slavery).
Orgoreyn seems like a friendly enough place. The people there live in a communal society, and this means they all work for the state. In return, the state provides them houses and jobs. (Getting the picture? Think "Soviet Union" circa about the 1960s.) Unfortunately, the airs of equality only serve to mask a hideous truth.
The people in power at Orgoreyn use their so-called equality to keep themselves in power while everyone else gets not-so-much power. They monitor all communications and information throughout the country. They send political adversaries to Volunteer camps, and even brag about how efficiently they work. The state also raises children rather than the parents (you know, to make sure everything runs smoothly).
The equality of Orgoreyn only serves to hide their inequality out in the open. Unfortunately for Ai, who is not use to Gethenian ways, the plan works. He doesn't figure it out until it's almost too late.
Understanding the greater Hainish universe isn't required to enjoy The Left Hand of Darkness, but hey, it doesn't hurt either.
A long time ago in a galaxy really, really close by space standards, there was the planet Hain. The Hainish people were an advanced race that set about colonizing other planets, including Earth. As Ai tells King Argaven, "all the worlds of men were settled, eons ago, from one world, Hain. We vary, but we're all sons of the same Hearth" (3.34).
In Chapter 7, it is speculated that the Gethenians are genetic experiments preformed by the Hainish, one of several other experimental planets. No one knows why they preformed these experiments but our guess is, um, theme park.…?
Then an unknown variety of catastrophe struck. The Hainish Empire was wiped out, and all their colonized worlds eventually just forgot about them and kept evolving. This is where Le Guin's Hainish Cycle picks up.
The Hainish Cycle stories tell of the attempts to bring all the Hainish planets back into a centralized union. The League of All Worlds tries first, and their attempts appear in novels like The Dispossessed and Rocannon's World (we've got a "Brain Snack" on the chronology of the novels, if you're interested in giving them a taste). But it seems an alien race called the Shing destroyed the League at some point.
After the Shing threat ended, the Ekumen we know and love is formed to replace the League. (If you paid attention in history class, this might sound a lot like the United Nations replacing the League of Nations after World War II.) As Ai mentions, "Ekumen is our Terran word, in the common tongue it's called the Household; in Karhidish it would be the Hearth" (10.30). So far as we know, the Ekumen are still going strong in Le Guin's future history universe. But Le Guin is still writing, so we'll have to wait and see what fate awaits them.
There's just one more thing. Yeah, this book takes place in (presumably) some far-distant future—one where we've got interstellar spaceflight and faster-than-light communication. But the social concerns seem suspiciously familiar.
The 1960s in the United States and many other Western countries saw a pretty spectacular series of social changes. And we mean "spectacular" in the sense of "majorly major"; jury is still out on whether every single one of them was good.
Anyway, we're talking Civil Rights Acts, birth control, space flight, drugs, distrust of authority, Woodstock, hippies, war protest, the whole thing. Young people in the 1960s were all about protesting the old order and finding a new way of doing things. Like, questioning entrenched systems of power (such as that in Karhide); or working toward gender equality (such as that on Gethen).
Get the picture? Even though this book takes place in an entirely different galaxy, it has an experimental, almost naïve feeling about it that could only have come out of the 1960s.