How can I get a Bootstrap column to span multiple rows?

For Bootstrap 3:

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet"/>


<div class="row">
    <div class="col-md-4">
        <div class="well">1
            <br/>
            <br/>
            <br/>
            <br/>
            <br/>
        </div>
    </div>
    <div class="col-md-8">
        <div class="row">
            <div class="col-md-6">
                <div class="well">2</div>
            </div>
            <div class="col-md-6">
                <div class="well">3</div>
            </div>
        </div>
        <div class="row">
            <div class="col-md-6">
                <div class="well">4</div>
            </div>
            <div class="col-md-6">
                <div class="well">5</div>
            </div>
        </div>
    </div>
</div>
<div class="row">
    <div class="col-md-4">
        <div class="well">6</div>
    </div>
    <div class="col-md-4">
        <div class="well">7</div>
    </div>
    <div class="col-md-4">
        <div class="well">8</div>
    </div>
</div>

For Bootstrap 2:

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/2.3.2/css/bootstrap.min.css" rel="stylesheet"/>

<div class="row-fluid">
    <div class="span4"><div class="well">1<br/><br/><br/><br/><br/></div></div>
    <div class="span8">
        <div class="row-fluid">
            <div class="span6"><div class="well">2</div></div>
            <div class="span6"><div class="well">3</div></div>
        </div>
        <div class="row-fluid">
            <div class="span6"><div class="well">4</div></div>
            <div class="span6"><div class="well">5</div></div>
        </div>
    </div>
</div>
<div class="row-fluid">
    <div class="span4">
        <div class="well">6</div>
    </div>
    <div class="span4">
        <div class="well">7</div>
    </div>
    <div class="span4">
        <div class="well">8</div>
    </div>
</div>

See the demo on JSFiddle (Bootstrap 2): http://jsfiddle.net/SxcqH/52/

<div class="row">
  <div class="col-4 alert alert-primary">
     1
  </div>
  <div class="col-8">
    <div class="row">
      <div class="col-6 alert alert-primary">
        2
      </div>
      <div class="col-6 alert alert-primary">
        3
      </div>
      <div class="col-6 alert alert-primary">
        4
      </div>
      <div class="col-6 alert alert-primary">
        5
      </div>
    </div>
  </div>
</div>
<div class="row">
  <div class="col-4 alert alert-primary">
    6
  </div>
  <div class="col-4 alert alert-primary">
    7
  </div>
  <div class="col-4 alert alert-primary">
    8
  </div>
</div>

I believe the part regarding how to span rows has been answered thoroughly (i.e. by nesting rows), but I also ran into the issue of my nested rows not filling their container. While flexbox and negative margins are an option, a much easier solution is to use the predefined h-50 class on the row containing boxes 2, 3, 4, and 5.

Note: I am using Bootstrap-4, I just wanted to share because I ran into the same problem and found this to be a more elegant solution :)

Like the comments suggest, the solution is to use nested spans/rows.

<div class="container">
    <div class="row">
        <div class="span4">1</div>
        <div class="span8">
            <div class="row">
                <div class="span4">2</div>
                <div class="span4">3</div>
            </div>
            <div class="row">
                <div class="span4">4</div>
                <div class="span4">5</div>
            </div>
        </div>
    </div>
    <div class="row">
        <div class="span4">6</div>
        <div class="span4">7</div>
        <div class="span4">8</div>
    </div>
</div>