The system: People

To successfully change the culture within an organization, we need to understand the system we are operating in and how people within that system interact. This isn't as simple as it looks, so here is a standard map ...

People and Interactions over Processes and Tools ...

The above is a proximity model, where people who are more likely to interact are drawn in close vicinity. YMMV.

Your team

The first circle is your team. In case of Scrum, that would be the developers, the Product Owner and the Scrum Master.
Who interacts with whom, and how should these interactions look like? The Scrum Guide has a few things to say on mandatory Scrum interactions - for example, Planning, Refinement, Review or Retrospectives. Those are the objective, process-driven interactions.
What the Scrum Guide can't help you with: Who likes whom, who can work well together - and: which factors bring people closer together or further apart?
Detractors could be obvious stuff like different work ethics, fandom (Star Wars vs. Trekkies, for example), skill animosities (e.g, tester vs. coder) but also hidden things like subtle bigotry, not liking another person's choice of diet (e.g., garlic/onions) etc.
All of these will affect how well your team can interact. The good news? All of this is within your team's sphere of control - as long as you can talk about it, you can find a way to knit together.

Your organization

The second circle is your organization. Most traditional enterprises have roles such as team leads, middle managers, senior managers, finance, HR, marketing, sales, customer service etc.
All of these people will affect your team one way or another and the potential interaction points are already too many to count.
While the Scrum Guide states that the Scrum Master should protect the team from outside interference, it's hardly practical to create a complete bubble of isolation around the team. Especially in the early phases of an agile transition, the direct and indirect effects of managerial roles may still be very strong, oftentimes in detrimental ways. The solution can't be digging trenches - you'll need to provide education on the effects of any influence taken upon your team.
As management finds their new role within the changing organization, the interactions with classic business departments also change: the team gets closer to functions like sales, CSR or marketing - and these people, too, will need to learn which functions are better maintained within your team and which information needs to be communicated straight between the team and them.

I have heard many Scrum masters talk about "drawing boundaries" - while I personally would favour "blurring boundaries", i.e. integrating the different business people in ways that remove indirection and delay, right to the point where information is freely available and collaboration happens without structural limitation.

Immediate surrounding

Your company doesn't operate in a vacuum. There are many second-order interactions going on, the most important being between the customer and your organization. Depending on whether your team is working as business support or in marketable product development, it's a great idea to move the team as close as possible to (in the best case: directly into contact with) the customer.

In traditional organizations, you will see that sales people and marketing try to bond with the customer - which can be both a blessing and a curse for your team. These people, too, need to learn which second-degree interactions are helpful and which aren't. For example, making promises to the customer without consulting the team is oftentimes a recipe for disaster.

Then, there are suppliers and competitors. Suppliers may or may not have the flexibility to support your team's newfound ways of working, which can become a massive problem unless addressed. In many cases, vendors find themselves in an uncomfortable situation when their client(you) is asking for more flexibility, in terms of both contracts and speed.
Your competitors will strive to be more agile than you, so keep an eye on what they are doing at all times. As long as you can learn something from them, you have homework to do. In complex environments, your suppliers will also be working closely with your competitors - which can create extremely interesting dynamics that can become very dangerous for your organization unless properly managed.

And then there's all of those other second-degree interactions: Friends and family, (social) media. You can't possibly hope to change these people and we're quickly talking about thousands of possible interaction points for a single team, yet these do affect your team as well.

Never forget that these interactions are highly intertwined with all the other interactions previously mentioned: a single press release by Markting can cause hell to break loose within your team, while a careless blog post created by your developers could void a year's work of sales currying favour with a potential client.

At least the good news is that up to this point, the interactions are either directly under your team's sphere of control - or at least, they can be influenced one way or another. That means you need to be finding ways to make those interactions favorable for your team.

The world

Life would be simple if everything could be brought under control - but it's just not that simple: Imagine that you did everything right, and along comes a new law that makes your product illegal: What would you do? It's not as easy as having a chat with lawmakers and undoing the law.
There are so many forces far beyond your control which can devastate everything your team is doing. Thought leaders coming up with new ideas which might imply that you've been working in the wrong way, industry leaders disrupting your market segment, political leaders interfering with your entire industry - and you might have no way to deal with it other than to cope with it!

The impact of "world level" interactions can also be both harmful and helpful - for example, a new invention may boost your team (if management lets you take advantage of it) or favorable changes in the market may boost your sales, thereby your financial resources. There are also cases where new laws or political changes might work in your favour and drive customers straight to your company.
These same effects could be positive or negative - in some cases, both. For example, that new helpful invention might boost your team - but also force you to invest heavily into it, draining resources elsewhere. Or that new political situation might drive flocks of customers right to your company - while the necessary customization changes overburden your team!

The world is beyond influence and control. In the Cynefin Framework, it would correlate with the "Chaotic Domain". You can't shield your team from the world's influence on your organization (and therefore, your team). Unless you're in a highly lobbying segment with massive public influence,  you can't tell the people of the world how they should behave, and you can't educate the world, either.

When it comes to interactions between the world and your organization, your only strategy is - adapt. That's what "being agile" is all about.

Summary

None of these interactions can be completely neglected - yet which of these interactions are crucial for whom, and when, constantly changes, so you're shooting at moving targets.

I hope you liked this small introduction into "People of the System" and what their interactions mean for your team. If you are an agile coach, understand that you can't always work on all of these, so you will need to observe the most important interaction points and work directly to make them favorable for your team.

"Being agile" means making the interactions within your sphere of influence more favorable - and learning to get along better with the interactions that influence you.